Molecular solid

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Molecular_solid

 

Models of the packing of molecules in two molecular solids, carbon dioxide or Dry ice (a), and caffeine (c). The gray, red, and purple balls represent carbon, oxygen, and nitrogen, respectively. Images of carbon dioxide (b) and caffeine (d) in the solid state at room temperature and atmosphere. The gaseous phase of the dry ice in image (b) is visible because the molecular solid is subliming.

A molecular solid is a solid consisting of discrete molecules. The cohesive forces that bind the molecules together are van der Waals forces, dipole-dipole interactions, quadrupole interactions, π-π interactions, hydrogen bonding, halogen bonding, London dispersion forces, and in some molecular solids, coulombic interactions. Van der Waals, dipole interactions, quadrupole interactions, π-π interactions, hydrogen bonding, and halogen bonding (2-127 kJ mol⁻¹) are typically much weaker than the forces holding together other solids: metallic (metallic bonding, 400-500 kJ mol⁻¹), ionic (Coulomb’s forces, 700-900 kJ mol⁻¹), and network solids (covalent bonds, 150-900 kJ mol⁻¹). Intermolecular interactions, typically do not involve delocalized electrons, unlike metallic and certain covalent bonds. Exceptions are charge-transfer complexes such as the tetrathiafulvane-tetracyanoquinodimethane (TTF-TCNQ), a radical ion salt. These differences in the strength of force (i.e. covalent vs. van der Waals) and electronic characteristics (i.e. delocalized electrons) from other types of solids give rise to the unique mechanical, electronic, and thermal properties of molecular solids.

Molecular solids are poor electrical conductors, although some, such as TTF-TCNQ are semiconductors (ρ = 5 x 10² Ω⁻¹ cm⁻¹). They are still substantially less than the conductivity of copper (ρ = 6 x 10⁵ Ω⁻¹ cm⁻¹). Molecular solids tend to have lower fracture toughness (sucrose, K_Ic = 0.08 MPa m^1/2) than metal (iron, K_Ic = 50 MPa m^1/2), ionic (sodium chloride, K_Ic = 0.5 MPa m^1/2), and covalent solids (diamond, K_Ic = 5 MPa m^1/2). Molecular solids have low melting (T_m) and boiling (T_b) points compared to metal (iron), ionic (sodium chloride), and covalent solids (diamond). Examples of molecular solids with low melting and boiling temperatures include argon, water, naphthalene, nicotine, and caffeine (see table below). The constituents of molecular solids range in size from condensed monatomic gases to small molecules (i.e. naphthalene and water) to large molecules with tens of atoms (i.e. fullerene with 60 carbon atoms).

Melting and boiling points of metallic, ionic, covalent, and molecular solids.

Type of Solid	Material	Tm (°C)	Tb (°C)
Metallic	Iron	1,538	2,861
Ionic	Sodium chloride	801	1,465
Covalent	Diamond	4,440	-
Molecular	Argon	-189.3	-185.9
Molecular	Water	0	100
Molecular	Naphthalene	80.1	217.9
Molecular	Nicotine	-79	491
Molecular	Caffeine	235.6	519.9

Composition and structure

Molecular solids may consist of single atoms, diatomic, and/or polyatomic molecules. The intermolecular interactions between the constituents dictate how the crystal lattice of the material is structured. All atoms and molecules can partake in van der Waals and London dispersion forces (sterics). It is the lack or presence of other intermolecular interactions based on the atom or molecule that affords materials unique properties.

Van der Waals forces

Van der Waals and London dispersion forces guide iodine to condense into a solid at room temperature. (a) A lewis dot structure of iodine and an analogous structure as a spacefill model. Purple balls represent iodine atoms. (b) Demonstration of how van der Waals and London dispersion forces guide the organization of the crystal lattice from 1D to 3D (bulk material).

Argon, is a noble gas that has a full octet, no charge, and is nonpolar. These characteristics make it unfavorable for argon to partake in metallic, covalent, and ionic bonds as well as most intermolecular interactions. It can though partake in van der Waals and London dispersion forces. These weak self-interactions are isotropic and result in the long-range ordering of the atoms into face centered cubic packing when cooled below -189.3. Similarly iodine, a linear diatomic molecule has a net dipole of zero and can only partake in van der Waals interactions that are fairly isotropic. This results in the bipyramidal symmetry.

Dipole-dipole and quadrupole interactions

The dipole-dipole interactions between the acetone molecules partially guide the organization of the crystal lattice structure. (a) A dipole-dipole interaction between acetone molecules stacked on top of one another. (b) A dipole-dipole interaction between acetone molecules in front and bock of each other in the same plane. (c) A dipole-dipole interaction between acetone molecules flipped in direction, but adjacent to each other in the same plane. (d) Demonstration of how quadrupole-quadrupole interactions are involved in the crystal lattice structure.

For acetone dipole-dipole interactions are a major driving force behind the structure of its crystal lattice. The negative dipole is caused by oxygen. Oxygen is more electronegative than carbon and hydrogen, causing a partial negative (δ-) and positive charge (δ+) on the oxygen and remainder of the molecule, respectively. The δ- orienttowards the δ+ causing the acetone molecules to prefer to align in a few configurations in a δ- to δ+ orientation (pictured left). The dipole-dipole and other intermolecular interactions align to minimize energy in the solid state and determine the crystal lattice structure.

The quadrupole-quadrupole interactions between the naphthalene molecules partially guide the organization of the crystal lattice structure. (a) A lewis dot structure artificially colored to provide a qualitative map of where the partial charges exist for the quadrupole. A 3D representation of naphthalene molecules and quadrupole. (b) A 3D representation of the quadrupole from two naphthalene molecules interacting. (c) A dipole-dipole interaction between acetone molecules flipped in direction, but adjacent to each other in the same plane. (c) Demonstration of how quadrupole-quadrupole interactions are involved in the crystal lattice structure.

A quadrupole, like a dipole, is a permanent pole but the electric field of the molecule is not linear as in acetone, but in two dimensions. Examples of molecular solids with quadrupoles are octafluoronaphthalene and naphthalene. Naphthalene consists of two joined conjugated rings. The electronegativity of the atoms of this ring system and conjugation cause a ring current resulting in a quadrupole. For naphthalene, this quadrupole manifests in a δ- and δ+ accumulating within and outside the ring system, respectively. Naphthalene assembles through the coordination of δ- of one molecules to the δ+ of another molecule. This results in 1D columns of naphthalene in a herringbone configuration. These columns then stack into 2D layers and then 3D bulk materials. Octafluoronaphthalene follows this path of organization to build bulk material except the δ- and δ+ are on the exterior and interior of the ring system, respectively.

Hydrogen and halogen bonding

The hydrogen bonding between the acetic acid molecules partially guides the organization of the crystal lattice structure. (a) A lewis dot structure with the partial charges and hydrogen bond denoted with blue dashed line. A ball and stick model of acetic acid with hydrogen bond denoted with blue dashed line. (b) Four acetic acid molecules in zig-zag hydrogen bonding in 1D. (c) Demonstration of how hydrogen bonding are involved in the crystal lattice structure.

A hydrogen bond is a specific dipole where a hydrogen atom has a partial positive charge (δ+) to due a neighboring electronegative atom or functional group. Hydrogen bonds are amongst the strong intermolecular interactions know other than ion-dipole interactions. For intermolecular hydrogen bonds the δ+ hydrogen interacts with a δ- on an adjacent molecule. Examples of molecular solids that hydrogen bond are water, amino acids, and acetic acid. For acetic acid, the hydrogen (δ+) on the alcohol moiety of the carboxylic acid hydrogen bonds with other the carbonyl moiety (δ-) of the carboxylic on the adjacent molecule. This hydrogen bond leads a string of acetic acid molecules hydrogen bonding to minimize free energy. These strings of acetic acid molecules then stack together to build solids.

The halogen bonding between the bromine and 1,4-dioxane molecules partially guides the organization of the crystal lattice structure. (a) A lewis dot structure and ball and stick model of bromine and 1,4-dioxane. The halogen bond is between the bromine and 1,4-dioxane. (b) Demonstration of how halogen bonding can guide the crystal lattice structure.

A halogen bond is when an electronegative halide participates in a noncovalent interaction with a less electronegative atom on an adjacent molecule. Examples of molecular solids that halogen bond are hexachlorobenzene and a cocrystal of bromine 1,4-dioxane. For the second example, the δ- bromine atom in the diatomic bromine molecule is aligning with the less electronegative oxygen in the 1,4-dioxane. The oxygen in this case is viewed as δ+ compared to the bromine atom. This coordination results in a chain-like organization that stack into 2D and then 3D.

Coulombic interactions

The partial ionic bonding between the TTF and TCNQ molecules partially guides the organization of the crystal structure. The van der Waals interactions of the core for TTF and TCNQ guide adjacent stacked columns. (a) A lewis dot structure and ball and stick model of TTF and TCNQ. The partial ionic bond is between the cyano- and thio- motifs. (b) Demonstration of how van der Waals and partial ionic bonding guide the crystal lattice structure.

Coulombic interactions are manifested in some molecular solids. A well-studied example is the radical ion salt TTF-TCNQ with a conductivity of 5 x 10² Ω⁻¹ cm⁻¹, much closer to copper (ρ = 6 x 10⁵ Ω⁻¹ cm⁻¹) than many molecular solids. The coulombic interaction in TTF-TCNQ stems from the large partial negative charge (δ = -0.59) on the cyano- moiety on TCNQ at room temperature. For reference, a completely charged molecule δ = ±1. This partial negative charge leads to a strong interaction with the thio- moiety of the TTF. The strong interaction leads to favorable alignment of these functional groups adjacent to each other in the solid state. While π-π interactions cause the TTF and TCNQ to stack in separate columns.

Allotropes

One form of an element may be a molecular solid, but another form of that same element may not be a molecular solid. For example, solid phosphorus can crystallize as different allotropes called "white", "red", and "black" phosphorus. White phosphorus forms molecular crystals composed of tetrahedral P₄ molecules. Heating at ambient pressure to 250 °C or exposing to sunlight converts white phosphorus to red phosphorus where the P₄ tetrahedra are no longer isolated, but connected by covalent bonds into polymer-like chains. Heating white phosphorus under high (GPa) pressures converts it to black phosphorus which has a layered, graphite-like structure.

The structural transitions in phosphorus are reversible: upon releasing high pressure, black phosphorus gradually converts into the red phosphorus, and by vaporizing red phosphorus at 490 °C in an inert atmosphere and condensing the vapor, covalent red phosphorus can be transformed into the molecular solid, white phosphorus.

White, red, violet, and black phosphorus samples	Structure unit of white phosphorus		Structures of red	violet	and black phosphorus

Similarly, yellow arsenic is a molecular solid composed of As₄ units. Some forms of sulfur and selenium are composed of S₈ (or Se₈) units and are molecular solids at ambient conditions, but converted into covalent allotropes having atomic chains extending throughout the crystal.

Properties

Since molecular solids are held together by relatively weak forces they tend to have low melting and boiling points, low mechanical strength, low electrical conductivity, and poor thermal conductivity. Also, depending on the structure of the molecule, the intermolecular forces may have directionality leading to anisotropy of certain properties.

Melting and boiling points

The characteristic melting point of metals and ionic solids is ~ 1000 °C and greater, while molecular solids typically melt closer to 300 °C (see table), thus many corresponding substances are either liquid (ice) or gaseous (oxygen) at room temperature. This is due to the elements involved, the molecules they form, and the weak intermolecular interactions of the molecules.

Allotropes of phosphorus are useful to further demonstrate this structure-property relationship. White phosphorus, a molecular solid, has a relatively low density of 1.82 g/cm³ and melting point of 44.1 °C; it is a soft material which can be cut with a knife. When it is converted to the covalent red phosphorus, the density goes to 2.2–2.4 g/cm³ and melting point to 590 °C, and when white phosphorus is transformed into the (also covalent) black phosphorus, the density becomes 2.69–3.8 g/cm³ and melting temperature ~200 °C. Both red and black phosphorus forms are significantly harder than white phosphorus.

Mechanical properties

Molecular solids can be either ductile or brittle, or a combination depending on the crystal face stressed. Both ductile and brittle solids undergo elastic deformation till they reach the yield stress. Once the yield stress is reached ductile solids undergo a period of plastic deformation, and eventually fracture. Brittle solids fracture promptly after passing the yield stress. Due to the asymmetric structure of most molecules, many molecular solids have directional intermolecular forces. This phenomenon can lead to anisotropic mechanical properties. Typically a molecular solid is ductile when it has directional intermolecular interactions. This allows for dislocation between layers of the crystal much like metals.

One example of a ductile molecular solid, that can be bent 180°, is hexachlorobenzene (HCB). In this example the π-π interactions between the benzene cores are stronger than the halogen interactions of the chlorides. This difference leads to its flexibility. This flexibility is anisotropic; to bend HCB to 180° you must stress the [001] face of the crystal. Another example of a flexible molecular solid is 2-(methylthio)nicotinic acid (MTN). MTN is flexible due to its strong hydrogen bonding and π-π interactions creating a rigid set of dimers that dislocate along the alignment of their terminal methyls. When stressed on the [010] face this crystal will bend 180°. Note, not all ductile molecular solids bend 180° and some may have more than one bending faces.

Electrical properties

Molecular solids are generally insulators. This large band gap (compared to germanium at 0.7 eV) is due to the weak intermolecular interactions, which result in low charge carrier mobility. Some molecular solids exhibit electrical conductivity, such as TTF-TCNQ with ρ = 5 x 10² Ω⁻¹ cm⁻¹ but in such cases orbital overlap is evident in the crystal structure. Fullerenes, which are insulating, become conducting or even superconducting upon doping.

Thermal properties

Molecular solids have many thermal properties: specific heat capacity, thermal expansion, and thermal conductance to name a few. These thermal properties are determined by the intra- and intermolecular vibrations of the atoms and molecules of the molecular solid. While transitions of an electron do contribute to thermal properties, their contribution is negligible compared to the vibrational contribution.

Physical chemistry

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Physical_chemistry

 

Between the flame and the flower is aerogel, whose synthesis has been aided greatly by physical chemistry.

Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria.

Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids).

Some of the relationships that physical chemistry strives to resolve include the effects of:

1. Intermolecular forces that act upon the physical properties of materials (plasticity, tensile strength, surface tension in liquids).
2. Reaction kinetics on the rate of a reaction.
3. The identity of ions and the electrical conductivity of materials.
4. Surface science and electrochemistry of cell membranes.
5. Interaction of one body with another in terms of quantities of heat and work called thermodynamics.
6. Transfer of heat between a chemical system and its surroundings during change of phase or chemical reaction taking place called thermochemistry
7. Study of colligative properties of number of species present in solution.
8. Number of phases, number of components and degree of freedom (or variance) can be correlated with one another with help of phase rule.
9. Reactions of electrochemical cells.
10. Behaviour of microscopic systems using quantum mechanics and macroscopic systems using statistical thermodynamics.
11. Calculation of the Energy of electron movement in a metal complexes.

Key concepts

The key concepts of physical chemistry are the ways in which pure physics is applied to chemical problems.

One of the key concepts in classical chemistry is that all chemical compounds can be described as groups of atoms bonded together and chemical reactions can be described as the making and breaking of those bonds. Predicting the properties of chemical compounds from a description of atoms and how they bond is one of the major goals of physical chemistry. To describe the atoms and bonds precisely, it is necessary to know both where the nuclei of the atoms are, and how electrons are distributed around them.

Disciplines

Quantum chemistry, a subfield of physical chemistry especially concerned with the application of quantum mechanics to chemical problems, provides tools to determine how strong and what shape bonds are, how nuclei move, and how light can be absorbed or emitted by a chemical compound. Spectroscopy is the related sub-discipline of physical chemistry which is specifically concerned with the interaction of electromagnetic radiation with matter.

Another set of important questions in chemistry concerns what kind of reactions can happen spontaneously and which properties are possible for a given chemical mixture. This is studied in chemical thermodynamics, which sets limits on quantities like how far a reaction can proceed, or how much energy can be converted into work in an internal combustion engine, and which provides links between properties like the thermal expansion coefficient and rate of change of entropy with pressure for a gas or a liquid. It can frequently be used to assess whether a reactor or engine design is feasible, or to check the validity of experimental data. To a limited extent, quasi-equilibrium and non-equilibrium thermodynamics can describe irreversible changes. However, classical thermodynamics is mostly concerned with systems in equilibrium and reversible changes and not what actually does happen, or how fast, away from equilibrium.

Which reactions do occur and how fast is the subject of chemical kinetics, another branch of physical chemistry. A key idea in chemical kinetics is that for reactants to react and form products, most chemical species must go through transition states which are higher in energy than either the reactants or the products and serve as a barrier to reaction. In general, the higher the barrier, the slower the reaction. A second is that most chemical reactions occur as a sequence of elementary reactions, each with its own transition state. Key questions in kinetics include how the rate of reaction depends on temperature and on the concentrations of reactants and catalysts in the reaction mixture, as well as how catalysts and reaction conditions can be engineered to optimize the reaction rate.

The fact that how fast reactions occur can often be specified with just a few concentrations and a temperature, instead of needing to know all the positions and speeds of every molecule in a mixture, is a special case of another key concept in physical chemistry, which is that to the extent an engineer needs to know, everything going on in a mixture of very large numbers (perhaps of the order of the Avogadro constant, 6 x 10²³) of particles can often be described by just a few variables like pressure, temperature, and concentration. The precise reasons for this are described in statistical mechanics, a specialty within physical chemistry which is also shared with physics. Statistical mechanics also provides ways to predict the properties we see in everyday life from molecular properties without relying on empirical correlations based on chemical similarities.

History

See also: History of chemistry

 

Fragment of M. Lomonosov's manuscript 'Physical Chemistry' (1752)

The term "physical chemistry" was coined by Mikhail Lomonosov in 1752, when he presented a lecture course entitled "A Course in True Physical Chemistry" (Russian: Курс истинной физической химии) before the students of Petersburg University. In the preamble to these lectures he gives the definition: "Physical chemistry is the science that must explain under provisions of physical experiments the reason for what is happening in complex bodies through chemical operations".

Modern physical chemistry originated in the 1860s to 1880s with work on chemical thermodynamics, electrolytes in solutions, chemical kinetics and other subjects. One milestone was the publication in 1876 by Josiah Willard Gibbs of his paper, On the Equilibrium of Heterogeneous Substances. This paper introduced several of the cornerstones of physical chemistry, such as Gibbs energy, chemical potentials, and Gibbs' phase rule.

The first scientific journal specifically in the field of physical chemistry was the German journal, Zeitschrift für Physikalische Chemie, founded in 1887 by Wilhelm Ostwald and Jacobus Henricus van 't Hoff. Together with Svante August Arrhenius, these were the leading figures in physical chemistry in the late 19th century and early 20th century. All three were awarded the Nobel Prize in Chemistry between 1901 and 1909.

Developments in the following decades include the application of statistical mechanics to chemical systems and work on colloids and surface chemistry, where Irving Langmuir made many contributions. Another important step was the development of quantum mechanics into quantum chemistry from the 1930s, where Linus Pauling was one of the leading names. Theoretical developments have gone hand in hand with developments in experimental methods, where the use of different forms of spectroscopy, such as infrared spectroscopy, microwave spectroscopy, electron paramagnetic resonance and nuclear magnetic resonance spectroscopy, is probably the most important 20th century development.

Further development in physical chemistry may be attributed to discoveries in nuclear chemistry, especially in isotope separation (before and during World War II), more recent discoveries in astrochemistry, as well as the development of calculation algorithms in the field of "additive physicochemical properties" (practically all physicochemical properties, such as boiling point, critical point, surface tension, vapor pressure, etc.—more than 20 in all—can be precisely calculated from chemical structure alone, even if the chemical molecule remains unsynthesized), and herein lies the practical importance of contemporary physical chemistry.

See Group contribution method, Lydersen method, Joback method, Benson group increment theory, quantitative structure–activity relationship

Journals

Main category: Physical chemistry journals

Some journals that deal with physical chemistry include Zeitschrift für Physikalische Chemie (1887); Journal of Physical Chemistry A (from 1896 as Journal of Physical Chemistry, renamed in 1997); Physical Chemistry Chemical Physics (from 1999, formerly Faraday Transactions with a history dating back to 1905); Macromolecular Chemistry and Physics (1947); Annual Review of Physical Chemistry (1950); Molecular Physics (1957); Journal of Physical Organic Chemistry (1988); Journal of Physical Chemistry B (1997); ChemPhysChem (2000); Journal of Physical Chemistry C (2007); and Journal of Physical Chemistry Letters (from 2010, combined letters previously published in the separate journals)

Historical journals that covered both chemistry and physics include Annales de chimie et de physique (started in 1789, published under the name given here from 1815 to 1914).

Branches and related topics

• Chemical thermodynamics
• Chemical kinetics
• Statistical mechanics
• Quantum chemistry
• Electrochemistry
• Photochemistry
• Surface chemistry
• Solid-state chemistry
• Spectroscopy
• Biophysical chemistry
• Materials science
• Physical organic chemistry
• Micromeritics

 

Freezing-point depression

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Freezing-point_depression

 

Workers spreading salt from a salt truck for deicing the road.

 

Freezing point depression is responsible for keeping ice cream soft below 0°C.

Freezing-point depression is a drop in the maximum temperature at which a substance freezes, caused when a smaller amount of another, non-volatile substance is added. Examples include adding salt into water (used in ice cream makers and for de-icing roads), alcohol in water, ethylene or propylene glycol in water (used in antifreeze in cars), adding copper to molten silver (used to make solder that flows at a lower temperature than the silver pieces being joined), or the mixing of two solids such as impurities into a finely powdered drug.

In all cases, the substance added/present in smaller amounts is considered the solute, while the original substance present in larger quantity is thought of as the solvent. The resulting liquid solution or solid-solid mixture has a lower freezing point than the pure solvent or solid because the chemical potential of the solvent in the mixture is lower than that of the pure solvent, the difference between the two being proportional to the natural logarithm of the mole fraction. In a similar manner, the chemical potential of the vapor above the solution is lower than that above a pure solvent, which results in boiling-point elevation. Freezing-point depression is what causes sea water (a mixture of salt and other compounds in water) to remain liquid at temperatures below 0 °C (32 °F), the freezing point of pure water.

Explanation

Using vapour pressure

The freezing point is the temperature at which the liquid solvent and solid solvent are at equilibrium, so that their vapor pressures are equal. When a non-volatile solute is added to a volatile liquid solvent, the solution vapour pressure will be lower than that of the pure solvent. As a result, the solid will reach equilibrium with the solution at a lower temperature than with the pure solvent. This explanation in terms of vapor pressure is equivalent to the argument based on chemical potential, since the chemical potential of a vapor is logarithmically related to pressure. All of the colligative properties result from a lowering of the chemical potential of the solvent in the presence of a solute. This lowering is an entropy effect. The greater randomness of the solution (as compared to the pure solvent) acts in opposition to freezing, so that a lower temperature must be reached, over a broader range, before equilibrium between the liquid solution and solid solution phases is achieved. Melting point determinations are commonly exploited in organic chemistry to aid in identifying substances and to ascertain their purity.

Due to concentration and entropy

In the liquid solution, the solvent is diluted by the addition of a solute, so that fewer molecules are available to freeze (a lower concentration of solvent exists in a solution versus pure solvent). Re-establishment of equilibrium is achieved at a lower temperature at which the rate of freezing becomes equal to the rate of liquefying. The solute is not occluding or preventing the solvent from solidifying, it is simply diluting it so there is a reduced probability of a solvent making an attempt at freezing in any given moment.

At the lower freezing point, the vapor pressure of the liquid is equal to the vapor pressure of the corresponding solid, and the chemical potentials of the two phases are equal as well.

Uses

The phenomenon of freezing-point depression has many practical uses. The radiator fluid in an automobile is a mixture of water and ethylene glycol. The freezing-point depression prevents radiators from freezing in winter. Road salting takes advantage of this effect to lower the freezing point of the ice it is placed on. Lowering the freezing point allows the street ice to melt at lower temperatures, preventing the accumulation of dangerous, slippery ice. Commonly used sodium chloride can depress the freezing point of water to about −21 °C (−6 °F). If the road surface temperature is lower, NaCl becomes ineffective and other salts are used, such as calcium chloride, magnesium chloride or a mixture of many. These salts are somewhat aggressive to metals, especially iron, so in airports safer media such as sodium formate, potassium formate, sodium acetate, and potassium acetate are used instead.

Pre-treating roads with salt relies on the warmer road surface to initially melt the snow and make a solution; Pre-treatment of bridges (which are colder than roads) does not typically work.

 

Dissolved solutes prevent sap and other fluids in trees from freezing in winter.

Freezing-point depression is used by some organisms that live in extreme cold. Such creatures have evolved means through which they can produce a high concentration of various compounds such as sorbitol and glycerol. This elevated concentration of solute decreases the freezing point of the water inside them, preventing the organism from freezing solid even as the water around them freezes, or as the air around them becomes very cold. Examples of organisms that produce antifreeze compounds include some species of arctic-living fish such as the rainbow smelt, which produces glycerol and other molecules to survive in frozen-over estuaries during the winter months. In other animals, such as the spring peeper frog (Pseudacris crucifer), the molality is increased temporarily as a reaction to cold temperatures. In the case of the peeper frog, freezing temperatures trigger a large-scale breakdown of glycogen in the frog's liver and subsequent release of massive amounts of glucose into the blood. With the formula below, freezing-point depression can be used to measure the degree of dissociation or the molar mass of the solute. This kind of measurement is called cryoscopy (Greek cryo = cold, scopos = observe; "observe the cold") and relies on exact measurement of the freezing point. The degree of dissociation is measured by determining the van 't Hoff factor i by first determining m_B and then comparing it to m_solute. In this case, the molar mass of the solute must be known. The molar mass of a solute is determined by comparing m_B with the amount of solute dissolved. In this case, i must be known, and the procedure is primarily useful for organic compounds using a nonpolar solvent. Cryoscopy is no longer as common a measurement method as it once was, but it was included in textbooks at the turn of the 20th century. As an example, it was still taught as a useful analytic procedure in Cohen's Practical Organic Chemistry of 1910, in which the molar mass of naphthalene is determined using a Beckmann freezing apparatus.

Laboratory uses

Freezing-point depression can also be used as a purity analysis tool when analyzed by differential scanning calorimetry. The results obtained are in mol%, but the method has its place, where other methods of analysis fail.

In the laboratory, lauric acid may be used to investigate the molar mass of an unknown substance via the freezing-point depression. The choice of lauric acid is convenient because the melting point of the pure compound is relatively high (43.8 °C). Its cryoscopic constant is 3.9 °C·kg/mol. By melting lauric acid with the unknown substance, allowing it to cool, and recording the temperature at which the mixture freezes, the molar mass of the unknown compound may be determined.

This is also the same principle acting in the melting-point depression observed when the melting point of an impure solid mixture is measured with a melting-point apparatus since melting and freezing points both refer to the liquid-solid phase transition (albeit in different directions).

In principle, the boiling-point elevation and the freezing-point depression could be used interchangeably for this purpose. However, the cryoscopic constant is larger than the ebullioscopic constant, and the freezing point is often easier to measure with precision, which means measurements using the freezing-point depression are more precise.

FPD measurements are also used in the dairy industry to ensure that milk has not had extra water added. Milk with a FPD of over 0.509 °C is considered to be unadulterated.

Formula

For dilute solution

Freezing temperature of seawater at different pressures and some substances as a function of salinity. See image description for source.

If the solution is treated as an ideal solution, the extent of freezing-point depression depends only on the solute concentration that can be estimated by a simple linear relationship with the cryoscopic constant ("Blagden's Law").

${\displaystyle \mathrm{\Delta }{T}_f\propto \frac{\text{Moles of dissolved species}}{\text{Mass of solvent}}}$

${\displaystyle \mathrm{\Delta }{T}_f=K_{f}bi}$

where:

• ${\displaystyle \mathrm{\Delta }{T}_f}$ is the decrease in freezing point, defined as the freezing point ${\displaystyle T_f^0}$ of the pure solvent minus the freezing point ${\displaystyle T_f}$ of the solution, as the formula above results in a positive value given that all factors are positive. From the ${\displaystyle \mathrm{\Delta }{T}_f}$ calculated using the formula above, the freezing point of the solution can then be calculated as ${\displaystyle T_f=T_f^0-\mathrm{\Delta }{T}_f}$.
• ${\displaystyle K_f}$, the cryoscopic constant, which is dependent on the properties of the solvent, not the solute. (Note: When conducting experiments, a higher k value makes it easier to observe larger drops in the freezing point.)
• ${\displaystyle b}$ is the molality (moles of solute per kilogram of solvent)
• ${\displaystyle i}$ is the van 't Hoff factor (number of ion particles per formula unit of solute, e.g. i = 2 for NaCl, 3 for BaCl₂).

Some values of the cryoscopic constant K_f for selected solvents:

Compound	Freezing point (°C)	Kf in K⋅kg/mol
Acetic acid	16.6	3.90
Benzene	5.5	5.12
Camphor	179.8	39.7
Carbon disulfide	−112	3.8
Carbon tetrachloride	−23	30
Chloroform	−63.5	4.68
Cyclohexane	6.4	20.2
Ethanol	−114.6	1.99
Ethyl ether	−116.2	1.79
Naphthalene	80.2	6.9
Phenol	41	7.27
Water	0	1.86

For concentrated solution

The simple relation above doesn't consider the nature of the solute, so it is only effective in a diluted solution. For a more accurate calculation at a higher concentration, for ionic solutes, Ge and Wang (2010) proposed a new equation:

${\displaystyle \mathrm{\Delta }{T}_{\text{F}}=\frac{\mathrm{\Delta }{H}_{T_{\text{F}}}^{\text{fus}}-2R{T}_{\text{F}}\cdot \ln a_{\text{liq}}-\sqrt{2\mathrm{\Delta }{C}_p^{\text{fus}}{T}_{\text{F}}^{2}R\cdot \ln a_{\text{liq}}+(\mathrm{\Delta }{H}_{T_{\text{F}}}^{\text{fus}}{)}^2}}{2\left(\frac{\mathrm{\Delta }{H}_{T_{\text{F}}}^{\text{fus}}}{T_{\text{F}}}+\frac{\mathrm{\Delta }{C}_p^{\text{fus}}}{2}-R\cdot \ln a_{\text{liq}}\right)}.}$

In the above equation, T_F is the normal freezing point of the pure solvent (273 K for water, for example); a_liq is the activity of the solvent in the solution (water activity for aqueous solution); ΔH^fus_TF is the enthalpy change of fusion of the pure solvent at T_F, which is 333.6 J/g for water at 273 K; ΔC^fus_p is the difference between the heat capacities of the liquid and solid phases at T_F, which is 2.11 J/(g·K) for water.

The solvent activity can be calculated from the Pitzer model or modified TCPC model, which typically requires 3 adjustable parameters. For the TCPC model, these parameters are available for many single salts.

Papua conflict

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Papua_conflict

 

Papua conflict
Papua province   Highland Papua province   Central Papua province   South Papua province   West Papua province, (including Southwest Papua formed in December 2022)
Date 1 October 1962 – present (60 years, 8 months and 28 days) Location Central Papua, Highland Papua, Papua, South Papua, and West Papua, Indonesia (New Guinea) Status Ongoing
Belligerents
Indonesia

Supported by:

Free Papua Movement

Supported by:
Units involved
Indonesian Army Kodam XVIII/Kasuari Kodam XVII/Cendrawasih Indonesian Police Mobile Brigade Corps Papua Regional Police West Papua Regional Police	Autonomous units affiliated with the TPNPB Volunteers from Papua New Guinea ULMWP Autonomous units affiliated with WPA KNPB
Strength
Unknown	Unknown
Casualties and losses
at least 72 soldiers and 34 policemen killed (2010 – March 2022)	at least 38 killed (2010 – March 2022)
Estimates vary between 100,000 to 500,000 deaths

The Papua conflict is an ongoing conflict in Western New Guinea between Indonesia and the Free Papua Movement (Indonesian: Organisasi Papua Merdeka, OPM). Subsequent to the withdrawal of the Dutch administration from the Netherlands New Guinea in 1962 and implementation of Indonesian administration in 1963, the Free Papua Movement has conducted a low-intensity guerrilla war against Indonesia through the targeting of its military, police, and civilian populations.

Papuan separatists have conducted protests and ceremonies, raising their flag for independence or calling for federation with Papua New Guinea, and accuse the Indonesian government of indiscriminate violence and of suppressing their freedom of expression. Indonesia has been accused of conducting a genocidal campaign against the indigenous inhabitants. In a 2007 book, author De R. G. Crocombe wrote that it has been estimated that between 100,000 and 300,000 Papuans had been killed by Indonesian security forces, and many women raped or subjected to other sexual violence. Research on violence toward Papuan women by the Papuan Women's Working Group together with the Asia Justice Rights (AJAR) found 64 out of 170 (or 4 out of 10) Papuan women surveyed in 2013, 2017, and the most recent study from 2019, found 65 out of 249 Papuan women experienced some form of state violence. According to previous study and former political prisoner Ambrosius Mulait, most violence against Papuan women happened because of domestic violence by husbands and Papuan cultural views toward wives considering they have been 'paid'.

Indonesian governance style has been compared to that of a police state, suppressing freedom of political association and political expression, although others have noted conflicts in Papua are instead caused by the near or total absence of state in some area. Women's rights activists, such as Fien Jarangga, support movement towards independence.

The Indonesian authorities continue to restrict foreign access to the region due to what they officially claim to be "safety and security concerns". Some organizations have called for a peacekeeping mission in the area.

Historical background

Overview

Main article: West New Guinea dispute

 

The Indonesian National Armed Forces has been accused of committing human rights abuses in Papua.

In December 1949, at the end of the Indonesian National Revolution, the Netherlands agreed to recognise Indonesian sovereignty over the territories of the former Dutch East Indies, with the exception of Western New Guinea, which the Dutch continued to hold as Netherlands New Guinea. The nationalist Indonesian government argued that it was the successor state to the whole of the Dutch East Indies and wanted to end the Dutch colonial presence in the archipelago. The Netherlands argued that the Papuans were ethnically different and that the Netherlands would continue to administer the territory until it was capable of self-determination. From 1950 onwards, the Dutch and the Western powers agreed that the Papuans should be given an independent state, but due to global considerations, mainly the Kennedy administration's concern to keep Indonesia on their side of the Cold War, the United States pressured the Dutch to sacrifice Papua's independence and transfer the territory to Indonesia.

In 1962, the Dutch agreed to relinquish the territory to temporary United Nations administration, signing the New York Agreement, which included a provision that a plebiscite would be held before 1969. The Indonesian military organised this vote, called the Act of Free Choice in 1969 to determine the population's views on the territory's future; the result was in favor of integration into Indonesia. In violation of the Agreement between Indonesia and the Netherlands, the vote was a show of hands in the presence of the Indonesian military, and only involved 1,025 hand picked people who were "forced at gunpoint" to vote for integration, much less than 1% of those who should have been eligible to vote. The legitimacy of the vote is hence disputed by independence activists who protest the military occupation of Papua by Indonesia. Indonesia is regularly accused of human rights abuses. They include attacks on OPM-sympathetic civilians and jailing people who raise West Papua's national Morning Star flag for treason.

Through the transmigration program, which since 1969 includes migration to Papua, about half of inhabitants of Indonesian Papua are migrants. Interracial marriages are increasing and the offspring of trans-migrants have come to see themselves as "Papuan" over their parents' ethnic group. As of 2010, 13,500 Papuan refugees live in exile in the neighbouring Papua New Guinea (PNG), and occasionally, the fighting spills over the border. As a result, the Papua New Guinea Defence Force (PNGDF) has set up patrols along PNG's western border to prevent infiltration by the OPM. Additionally, the PNG government has been expelling resident "border crossers" and making a pledge of no anti-Indonesian activity a condition for migrants' stay in PNG. Since the late 1970s, the OPM have made retaliatory "threats against PNG business projects and politicians for the PNGDF's operations against the OPM". The PNGDF has performed joint border patrols with Indonesia since the 1980s, although the PNGDF's operations against the OPM are "parallel".

Origins

Prior to the arrival of the Dutch, two Indonesian principalities known as the Sultanate of Tidore and the Sultanate of Ternate claimed dominion over Western New Guinea. In 1660, the Dutch recognized the Sultan of Tidore's sovereignty over New Guinea. It thus became notionally Dutch as the Dutch held power over Tidore. A century later, in 1793, Britain attempted a failed settlement near Manokwari. After almost 30 years, in 1824 Britain and the Netherlands agreed to divide the land; rendering the eastern half of the island as being under British control and the western half would become part of the Dutch East Indies.

In 1828, the Dutch established a settlement in Lobo (near Kaimana) which also failed. Almost 30 years later, the Germans established the first missionary settlement on an island near Manokwari. While in 1828 the Dutch claimed the south coast west of the 141st meridian and the north coast west of Humboldt Bay in 1848, Dutch activity in New Guinea was minimal until 1898 when the Dutch established an administrative center, which was subsequently followed by missionaries and traders. Under Dutch rule, commercial links were developed between West New Guinea and Eastern Indonesia. In 1883, New Guinea was divided between the Netherlands, Britain, and Germany; with Australia occupying the German territory in 1914. In 1901, the Netherlands formally purchased West New Guinea from the Sultanate of Tidore, incorporating it into the Dutch East Indies. During World War II, the territory was occupied by Japan but was later recaptured by the Allies, who restored Dutch rule.

The unification of Western New Guinea with Papua New Guinea was official Australian government policy for a short period of time in the 1960s, before Indonesia's annexation of the region. Generally, proposals regarding federation with Papua New Guinea are a minority view in the freedom movement. Arguments for federation generally focus around shared cultural identity between the two halves of the island.

Four years after the 17 August 1945 proclamation of Indonesian independence, the Indonesian National Revolution ended with the Dutch–Indonesian Round Table Conference in late 1949 at which the Netherlands agreed to transfer sovereignty to the United States of Indonesia, the successor state to the Dutch East Indies. However, the Dutch refused to include Netherlands New Guinea in the new Indonesian Republic and decided to assist and prepare it for independence as a separate country. It was agreed that the present status quo of the territory would be maintained and then negotiated bilaterally one year after the date of the transfer of sovereignty. This transfer formally occurred on 27 December 1949.

A year later, both Indonesia and the Netherlands were still unable to resolve their differences, which led Indonesian President Sukarno to accuse the Dutch of reneging on their promises to negotiate the handover of the territory. The Dutch were persistent in their argument that the territory did not belong to Indonesia because the Melanesian Papuans were ethnically and geographically different from Indonesians, and that the territory had always been administrated separately. On top of that, some Papuans did not participate in the Indonesian Revolution, and that educated Papuans at the time were split between those supporting Indonesian integration, those supporting Dutch colonial rules, and those supporting Papuan independence.

While at face-value, the Dutch seemed to have the Papuans’ interest at heart, political scientist Arend Lijphart disagreed. He argued that other underlying Dutch motives to prevent West New Guinea from joining Indonesia included the territory's lucrative economic resources, its strategic importance as a Dutch naval base, and its potential role for creating a Eurasian homeland, housing the Eurasians who had become displaced by the Indonesian National Revolution. The Dutch also wanted to maintain a regional presence and to secure their economic interests in Indonesia.

On the other hand, Indonesia regarded West New Guinea as an intrinsic part of the country on the basis that Indonesia was the successor state to the Dutch East Indies. Papuans participated in the momentous 1928 Youth Pledge, which is the first proclamation of an "Indonesian identity" which symbolically was attended by numerous ethnic youth groups from all over Indonesia. Indonesian irredentist sentiments were also inflamed by the fact that several Indonesian political prisoners (mainly leftist and communist from the failed 1926 uprising) had been interned at a remote prison camp north of Merauke called Boven-Digoel in 1935 prior to World War II. They made contact with many Papuan civil servants which formed Indonesian revolution groups in Papua. Some support also came from native kingdoms mainly around Bomberai Peninsula which had extensive relationship with Sultanate of Tidore, these efforts was led by Machmud Singgirei Rumagesan, King of Sekar. These sentiments were also reflected in the popular Indonesian revolutionary slogan "Indonesia Merdeka- dari Sabang sampai Merauke" "Indonesia Free—from Sabang to Merauke. The slogan indicates the stretch of Indonesian territory from the most western part in Sumatra, Sabang, and the most eastern part in Merauke, a small city in West New Guinea. Sukarno also contended that the continuing Dutch presence in West New Guinea was an obstacle to the process of nation-building in Indonesia and that it would also encourage secessionist movements.

Bilateral negotiations (1950–1953)

The Netherlands and Indonesia tried to resolve the West New Guinea dispute through several rounds of bilateral negotiations between 1950 and 1953. These negotiations ended up to become unsuccessful and led the two governments to harden their stance and position. On 15 February 1952, the Dutch Parliament voted to incorporate New Guinea into the realm of the Netherlands and shortly after, the Netherlands refused further discussion on the question of sovereignty and considered the issue to be closed. In response, President Sukarno adopted a more forceful stance towards the Dutch. Initially, he unsuccessfully tried to force the Indonesian government to abrogate the Round Table agreements and to adopt economic sanctions but was rebuffed by the Natsir Cabinet. Undeterred by this setback, Sukarno made recovering the territory a top priority of his presidency and sought to harness popular support from the Indonesian public for this goal throughout many of his speeches between 1951 and 1952.

By 1953, the dispute had become the central issue in Indonesian domestic politics. All political parties across the political spectrum, particularly the Communist Party of Indonesia (PKI), supported Sukarno's efforts to integrate the territory into Indonesia. According to historians Audrey and George McTurnan Kahin, the PKI's pro-integration stance helped the party to rebuild its political base and to further its credentials as a nationalist Communist Party that supported Sukarno.

United Nations (1954–1957)

In 1954, Indonesia decided to take the dispute to the United Nations and succeeded in having it placed on the agenda for the upcoming ninth session of the United Nations General Assembly (UNGA). In response, the Dutch Ambassador to the United Nations, Herman van Roijen, warned that the Netherlands would ignore any recommendations which might be made by the UN regarding the dispute. During the Bandung Conference in April 1955, Indonesia succeeded in securing a resolution supporting its claim to West New Guinea from African and Asian countries. In addition, Indonesia was also supported by the Soviet Union and its Warsaw Pact allies.

In terms of international support, the Netherlands was supported by the United States, the United Kingdom, Australia, New Zealand, and several Western European and Latin American countries. However, these countries were unwilling to commit to providing military support in the event of a conflict with Indonesia. The Eisenhower administration were open to non-violent territorial changes but rejected the use of any military means to resolve the dispute. Until 1961, the United States pursued a policy of strict neutrality and abstained on every vote on the dispute. According to the historian Nicholas Tarling, the United Kingdom took the position that it was "strategically undesirable" for control of the territory to pass to Indonesia because it created a precedent for encouraging territorial changes based on political prestige and geographical proximity.

The Australian Menzies government welcomed the Dutch presence in the region as an "essential link" in its national defense since it also administrated a trust territory in the eastern half of New Guinea. Unlike the Labor Party which had supported the Indonesian nationalists, the Prime Minister Robert Menzies viewed Indonesia as a potential threat to its national security and distrusted the Indonesian leadership for supporting Japan during World War II. In addition, New Zealand and South Africa also opposed Indonesia's claim to the territory. New Zealand accepted the Dutch argument that the Papuans were culturally different from the Indonesians and thus supported maintaining Dutch sovereignty over the territory until the Papuans were ready for self-rule. By contrast, newly independent India, another Commonwealth member supported Indonesia's position.

Between 1954 and 1957, Indonesia and their Afro-Asian allies made three attempts to get the United Nations to intervene. All these three resolutions, however, failed to gain a two–thirds majority in the UNGA. On 30 November 1954, the Indian representative Krishna Menon initiated a resolution calling for Indonesia and the Netherlands to resume negotiations and to report to the 10th UNGA Session. This resolution was sponsored by eight countries (Argentina, Costa Rica, Cuba, Ecuador, El Salvador, India, Syria, and Yugoslavia) but failed to secure a two-thirds majority (34–23–3). In response to growing tensions between Jakarta and the Hague, Indonesia unilaterally dissolved the Netherlands-Indonesian Union on 13 February 1956, and also rescinded compensation claims to the Dutch. Undeterred by this setback, Indonesia resubmitted the dispute to the UNGA agenda in November 1965.

On 23 February 1957, a 13 country–sponsored resolution (Bolivia, Burma, Ceylon, Costa Rica, Ecuador, India, Iraq, Pakistan, Saudi Arabia, Sudan, Syria, and Yugoslavia) calling for the United Nations to appoint a "good offices commission" for West New Guinea was submitted to the UNGA. Despite receiving a plural majority (40–25–13), this second resolution failed to gain a two-thirds majority. Undeterred, the Afro-Asian caucus in the United Nations lobbied for the dispute to be included on the UNGA agenda. On 4 October 1957, Indonesia's Foreign Minister Subandrio warned that Indonesia would embark on "another cause" if the United Nations failed to bring about a solution to the dispute that favoured Indonesia. That month, the PKI and affiliated trade unions lobbied for retaliatory economic measures against the Dutch. On 26 November 1957, a third Indonesian resolution on the West New Guinea dispute was put to the vote but failed to gain a two-thirds majority (41–29–11).

West Papua's national identity

Following the recent defeat at the UN, Indonesia embarked on a national campaign targeting Dutch interests in Indonesia; leading to the withdrawal of the Dutch flag carrier KLM's landing rights, mass demonstrations, and the seizure of the Dutch shipping line Koninklijke Paketvaart-Maatschappij (KPM), Dutch-owned banks, and other estates. By January 1958, 10,000 Dutch nationals had left Indonesia, many returning to the Netherlands. This spontaneous nationalisation had adverse repercussions on Indonesia's economy, disrupting communications and affecting the production of exports. President Sukarno also abandoned efforts to raise the dispute at the 1958 UNGA, claiming that reason and persuasion had failed. Following a sustained period of harassment against Dutch diplomatic representatives in Jakarta, Indonesia formally severed relations with the Netherlands in August 1960.

In response to Indonesian aggression, the Netherlands stepped up its efforts to prepare the Papuans for self-determination in 1959. These efforts culminated in the establishment of a hospital in Hollandia (modern–day Jayapura), a shipyard in Manokwari, agricultural research sites, plantations, and a military force known as the Papuan Volunteer Corps. By 1960, a legislative New Guinea Council had been established with a mixture of legislative, advisory and policy functions had been established. Half of its members were to be elected and elections for this council were held the following year. Most importantly, the Dutch also sought to create a sense of West Papuan national identity and these efforts led to the creation of a national flag (the Morning Star flag), a national anthem, and a coat of arms. The Dutch had planned to transfer independence to West New Guinea in 1970.

Preparation for independence

By 1960, other countries in the Asia-Pacific had taken notice of the dispute and began proposing initiatives to end it. During a visit to the Netherlands, the New Zealand Prime Minister Walter Nash suggested the idea of a united New Guinea state, consisting of both Dutch and Australian territories. This idea received little support from both Indonesia and other Western governments. Later that year, the Malayan Prime Minister Tunku Abdul Rahman proposed a three-step initiative, which involved West New Guinea coming under United Nations trusteeship. The joint administrators would be three non-aligned nations Ceylon, India, and Malaya, which supported Indonesia's position. This solution involved the two belligerents, Indonesia and the Netherlands, re-establishing bilateral relations and the return of Dutch assets and investments to their owners. However, this initiative was scuttled in April 1961 due to opposition from Indonesia's Foreign Minister Subandrio, who publicly attacked Tunku's proposal.

By 1961, the Netherlands was struggling to find adequate international support for its policy to prepare West New Guinea for independent status under Dutch guidance. While the Netherlands' traditional Western allies—the United States, Great Britain, Australia, and New Zealand—were sympathetic to Dutch policy, they were unwilling to provide any military support in the event of conflict with Indonesia. On 26 September 1961, the Dutch Foreign Minister Joseph Luns offered to hand over the territory to a United Nations trusteeship. This proposal was firmly rejected by his Indonesian counterpart Subandrio, who likened the dispute to Katanga's attempted secession from the Republic of Congo during the Congo Crisis. By October 1961, Britain was open to transferring West New Guinea to Indonesia while the United States floated the idea of a jointly-administered trusteeship over the territory.

Call for resumption of Dutch–Indonesian talks

On 23 November 1961, the Indian delegation at the United Nations presented a draft resolution calling for the resumption of Dutch–Indonesian talks on terms which favoured Indonesia. Two days later, several Francophone countries in Africa tabled a rival resolution which favoured an independent West New Guinea. Indonesia favoured India's resolution while the Dutch, Britain, Australia, and New Zealand supported the Francophone African one. On 27 November 1961, both the Francophone African (52–41–9) and Indian (41–40–21) resolutions were put to the vote, but neither succeeded in gaining a two–thirds majority at the UNGA. The failure of this final round of diplomacy in the UN convinced Indonesia to prepare for a military invasion.

New York Agreement, UN administration and Act of Free Choice

Main article: New York Agreement

See also: West New Guinea dispute

By 1961, the United States had become concerned about the Indonesian military's purchase of Soviet weapons and equipment for a planned invasion of West New Guinea. The Kennedy administration feared an Indonesian drift towards Communism and wanted to court Sukarno away from the Soviet bloc and Communist China. The United States also wanted to repair relations with Jakarta, which had deteriorated due to the Eisenhower administration's covert support for regional uprisings in Sumatra and Sulawesi. These factors convinced the Kennedy administration to intervene diplomatically to bring about a peaceful solution to the dispute, which favored Indonesia.

Throughout 1962, US diplomat Ellsworth Bunker facilitated top–secret high–level negotiations between Indonesia and the Netherlands. This produced a peace settlement known as the New York Agreement on 15 August 1962. As a face-saving measure, the Dutch would hand over West New Guinea to a provisional United Nations Temporary Executive Authority (UNTEA) on 1 October 1962, which then ceded the territory to Indonesia on 1 May 1963; formally ending the dispute. As part of the agreement, it was stipulated that a popular plebiscite would be held in 1969 to determine whether the Papuans would choose to remain in Indonesia or seek self-determination. Implementation of Indonesian governance was followed by sporadic fighting between Indonesian and pro-Papuan forces until 1969.

Following the Act of Free Choice plebiscite in 1969, Western New Guinea was formally integrated into the Republic of Indonesia. Instead of a referendum of the 816,000 Papuans, only 1,022 Papuan tribal representatives were allowed to vote, and they were coerced into voting in favour of integration. While several international observers including journalists and diplomats criticised the referendum as being rigged, the U.S. and Australia support Indonesia's efforts to secure acceptance in the United Nations for the pro-integration vote. That same year, 84 member states voted in favour for the United Nations to accept the result, with 30 others abstaining. A number of Papuans refused to accept the territory's integration into Indonesia, which anti-independence supporters and foreign observers attributed to the Netherlands' efforts to promote a West Papuan national identity among right-leaning Papuans and suppressed left-leaning Papuans pro-Indonesian sympathies. These formed the separatist Organisasi Papua Merdeka (Free Papua Movement) and have waged an insurgency against the Indonesian authorities, which continues to this day.