Chapter 16.4, Problem 47LC

Interpretation Introduction

Interpretation : The temperature at which ocean water will freeze has to be generalized. The effect the presence of dissolved elements in the ocean has on the rate of evaporation of ocean water has to be explained.

Concept Introduction : Colligative properties are those of solutions that depend only on the number of solute particles present, not on the nature of those particles. Depression in freezing point, elevation in boiling point, and vapor pressure lowering are important colligative properties.

Answer to Problem 47LC

The temperature at which ocean water will freeze will be lower than the water freezing temperature. The rate of evaporation of ocean water will be higher due to dissolved elements in the ocean.

Explanation of Solution

The elements dissolved in the oceans are chlorine, sodium, magnesium, sulfur, calcium, potassium, bromine, carbon, strontium and boron.

Due to the presence of solutes in the ocean, there is a change in its freezing point and boiling point.

The freezing point of the ocean decreases while the boiling point increases.

The boiling-point elevation is the temperature difference between a solution's boiling point and the boiling point of a pure solvent.

The likelihood of water turning into vapor is decreased by the solute due to the solution's vapor pressure being lowered.

To boil off the liquid water molecules, more kinetic energy will be needed.

The temperature of freezing ocean water will be lower than that of the freezing point of water.

This is due to freezing point depression.

The rate of evaporation of ocean water increases due to the presence of dissolved elements which cause boiling point elevation.