Question

Henry's law constant for a gas CH3Br is 0.19 mole decimeter cube inverse atm inverse at 25 degree Celsius. What is solubility of water at 25 degree Celsius and a partial pressure of 0.164 atm?

• A. 0.03116 mol dm^-3
• B. 0.19 mol dm^-3
• C. 0.164 mol dm^-3
• D. 0.003116 mol dm^-3

Answer 1

Answer: (A)

0.03116 mol dm^-3

Answer 2

Molarity is the parameter to express concentration of the solution and is defined as the amounts of moles of solute that are dissolved in per liter of solution.

Formula used: Henry’s law formula- $C={{K}_{H}}P$ where $C$ is the solubility (concentration) of the gas in the liquid, $K_H$ is Henry's law constant, and $P$ is the partial pressure of the gas.

Complete step by step solution: For the gas CH3Br, given in this question are: Henry’s law constant, $K_H = 0.19 \, \text{mol dm}^{-3} \, \text{atm}^{-1}$ Temperature $= 25{}^\circ C$ Partial pressure of the gas, $P = 0.164 \, \text{atm}$

According to Henry’s law, the solubility of a gas in a liquid is directly proportional to its partial pressure. So, solubility of the gas will be obtained by calculating its concentration using Henry’s formula: $C={{K}_{H}}P$ Substituting the given values: Henry’s constant, $K_H = 0.19 \, \text{mol dm}^{-3} \, \text{atm}^{-1}$ Pressure of the gas, $P = 0.164 \, \text{atm}$

Concentration of the gas in the solution (solubility) $C = (0.19 \, \text{mol dm}^{-3} \, \text{atm}^{-1}) \times (0.164 \, \text{atm})$ $C = 0.03116 \, \text{mol dm}^{-3}$

We know that molarity is expressed in terms of moles per liter. The conversion of volume unit is: $1 \, \text{dm}^3 = 1 \, \text{L}$ So, the solubility is expressed in terms of molarity as: Molarity $C = 0.03116 \, \text{mol L}^{-1}$