Question

Assignment Four Colligative properties refer to properties of the solvent that are affected by the presence/absence of solute particles. As such, they are dependent on the physical reaction of the solute and the solvent—there are no chemical reactions involved. All responses to the following questions should use language and terms that a high school senior that hasn't taken AP chemistry. 1) Why does the addition of solute decrease the melting point, and increase the boiling point of the solvent? 2) Under what situations could the addition of solute increase the melting point of the solute? 3) Baking recipes often have a different set of instructions for baking at higher elevations, due to the boiling point of water being lower. Is this an example of a colligative property? Why or why not?

Answer 1

Eperiment No. Eperiment Date (1) Melting (1) Melting Att which togther. point Solid point į the and equilirium temperature Tiquid states co-exist and tion 22 Bolling point is the equilibrium tempera- tire at which wapour pressure 7 Secomes equal to atmospheric pressure. - Metting Point is the equilibrich temperature at which vapour pressure of solid 8 liquid Secomes equalo => The Addition of Solute decreases the melting point of Solvent because of decrease of vapour Pressure of soment. This decrease in vapoun Pressure of sowent is due to decrease in escaping tendency of vapours of Sowent molecule because of the resistance from Solute molecules. As such, Ten Tolent molecules escape and Tes will be vapour pressure. Thus The sowent molecules will come to equilibrium only at higher temperature. J =) we can say Addition of Solute causes depression of freezing point. - Boiling point increases because Tess vaDours will come from solent. the escaping tendency of Sowent molecules deeremes because of resistance by soude molecules.

VO. Experimen Date => Thas to make vaboon Pressure of Solution equal to atmospheric pressure, high temperature is applied, which increase The Napour Dressure and equalises it to atmospheric pressure. => When Sucute added to solvent y Volatile in nature ne it also forms Nabours In addition to vapours of pure sowent. Due to this vapour pressure of overall Solution Increases and melting point increases. eig Alcohol & Ice. o Baking powder is basically NaHCO₂ t tant aric acid => There sauts are non-volatile in naturre and when added to pure water form Solutions. The Boiling point of such solutions is higher as compared to pure water. - The addition of solute restrict the evolution of vapours from Solvent. => This causes elevation in Boiling point - Elevation in Boiling point is a Colligative property.

DIAU comigative property only depends upon Number of moles of solute & is ' independant of Nature of sucute. BTS x 30 souter Sowent ATG = Tsouth suwert vapourt - - - - suktion preme To vapour-pressure carrves) equilibrium sowent, temperature) Tsol. Temperature Vapour pressure - netting helting point Solution. F t Melting Temperature Off = I sowat I suutron Alfa Depression in f solution st freezing point Solito ed Teacher's Signature los