Question

Give reasons: 
(a) Cooking is faster in a pressure cooker than in an open pan. 
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? 
© What change in temperature would you observe after mixing liquids X and Y? 

Hint:

Negative deviation from Raoult's law occurs when the intermolecular forces between the components of the solution are stronger than in the pure state, leading to a decrease in volume and an exothermic mixing process.

Answer 1

(a) Pressure Cooker Efficiency: A pressure cooker cooks food faster than an open pan due to increased internal pressure, which elevates the boiling point of water. This allows water to reach higher temperatures before boiling, accelerating the cooking process. In contrast, open pans boil water at a lower temperature, prolonging cooking times.

(b) Volume Contraction Upon Mixing Liquids X and Y: A decrease in volume upon mixing liquid X and liquid Y signifies molecular interactions causing closer packing, leading to reduced overall volume. This behavior demonstrates a negative deviation from Raoult's law, characteristic of mixtures where intermolecular forces between components are stronger than in the pure substances. 

(C) Temperature Change After Mixing Liquids X and Y: Negative deviations from Raoult's law typically involve exothermic mixing, resulting in a temperature increase. This occurs because the formation of stronger intermolecular interactions in the mixture releases energy.