Chapter 14, Problem 116A

Graph Table 14.10 shows solubility data that was collectedin an experiment. Plot a graph of the molarity ofKI versus temperature. What is the solubility of KI at55°C?

Interpretation Introduction

Interpretation:

The solubility of potassium iodide (KI) at 55 °Chave to be calculated.

Concept introduction:

Solubility: Solubility can be expressed as maximum amount of solute that can dissolve in known amount of solvent at a given temperature and pressure. Solubility depends upon the temperature of the solvent. This is why many substances are more soluble at high temperatures.

Answer to Problem 116A

The solubility of potassium iodideat 55 °C is almost 10.5 M.

Explanation of Solution

Molarity of the KI solution at different temperatures have to calculate first.

$\begin{array}{l}Molarityofthesolution=\frac{Numberofmolesof the solute}{ Volume of the solution(inlitre)}\\ Molarityofthesolution=\frac{Massof the solute}{ Molecularweightof the solute\times Volume of the solution(inlitre)}\end{array}$

1. Molarity of the KI solution at20°C

$Molarityofthesolution=\frac{144gm}{166gm/mol\times 0.1L}=8.67M$

2. Molarity of the KI solution at 40°C

$Molarityofthesolution=\frac{162gm}{166gm/mol\times 0.1L}=9.76M$

3. Molarity of the KI solution at 60°C

$Molarityofthesolution=\frac{176gm}{166gm/mol\times 0.1L}=10.6M$

4. Molarity of the KI solution at 80°C

$Molarityofthesolution=\frac{192gm}{166gm/mol\times 0.1L}=11.6M$

5. Molarity of the KI solution at 100°C

$Molarityofthesolution=\frac{206gm}{166gm/mol\times 0.1L}=12.4M$

Plotting the values of solubilities in molarity against temperature, we got

From the graph we can get the values of the solubility at different temperature. At 55°C, the solubility of KI is almost10.5 M.