The boiling point is the temperature at which a liquid’s vapor pressure equals the surrounding atmospheric pressure. When the temperature of a liquid reaches its boiling point, the gas can be converted to a vapour by adding heat. The boiling points of different substances are usually different for a given temperature. This is due to the strength of the intermolecular forces holding the substance together, which depend on the structure and arrangement of molecules within the substance.
The chemical compound potassium iodide, abbreviated to KI, is formed by the electrostatic attraction between positively charged potassium ions and negatively charged iodide ions. It is a white, crystalline solid and has a salty taste. KI is used as an ingredient in photographic film, pharmaceuticals, and nuclear medicine. It is soluble in water and has a density of 3.123 g/cm3.
When a solution of KI is heated, the atoms of the iodide ion are released from their bonds with potassium ions. As a result, the number of iodide atoms in the molecule decreases and the boiling point rises. This illustrates Dalton’s third postulate, which states that the atoms in a compound are neither created nor destroyed during a chemical reaction. The change in the boiling or freezing point of a solution is proportional to its molality, which is the number of moles of solute that are dissolved in the solvent. For example, a solution of magnesium iodide, MgI2, will have a higher boiling point than the solution of potassium iodide, because it has more molecules of MgI2 in it.