Chapter U5, Problem 4STP

Interpretation Introduction

Interpretation:

The process that correctly describes the condensation of water on the outside of a cold lemonade on a warm day needs to be identified from the given options.

Concept introduction:

Phase transition is a process when matter changes from one of the three states to another.

Evaporation, condensation, melting and freezing are some of the common phase transition processes

Chemical reactions in general involve an exchange of heat between the system (reactants and products) and the surroundings.

An endothermic process involves absorption of heat by the system from the surroundings, whereas an exothermic process involve liberation of heat by the system to the surroundings.

Answer to Problem 4STP

Option (B) is correct.

Explanation of Solution

Evaporation is a process which involves conversion of gas into vapor.

Condensation involves transition from vapor to liquid phase.

Melting involves transition from solid to liquid phase.

Freezing is a process in which a liquid gets converted into a solid.

It is mentioned that water condenses on the outside of cold lemonade on a warm day. This is a condensation reaction wherein water vapor from the warm atmosphere gets converted to liquid water as it hits the outside of the glass containing cold lemonade. Condensation reactions are exothermic and are accompanied by the transfer of energy to the surroundings.

Conclusion

Thus, as water vapor condenses energy is transferred to the surroundings thereby lowering the temperature of water molecules.