Q13-13.44 P - Chemistry: Molecular Nature Of Matter And Change

Question

For a saturated aqueous solution of each of the following at ${\mathbf{20}}^{\mathbf{o}}\mathbf{C}$  and 1atm, will the solubility increase, decrease, or stay the same when the indicated change occurs?

(a) ${\mathbf{O}}_{\mathbf{2}}\left(\mathbf{g}\right)$, increase P

(b)${\mathbf{N}}_{\mathbf{2}}\left(\mathbf{g}\right)$ , increase V

Step-by-Step Solution

Answer

1. The solubility of the oxygen gas increases as the pressure of the gas increases.
2. The solubility of the nitrogen gas decreases as the volume of the gas increases because the pressure of the gas decreases.

Step 1: Subpart (a) Effect of Pressure on O 2 g .

Solubility is defined as how much a solvent can take in solute when dissolved.

 

Of the three types of solutions, a saturated solution can be formed when there is solute to fill the spaces in the solvent and there is no more space to dissolve the solute.

 

As per Henry’s law, as the pressure of the gas increases, the solubility of the solute increases.

 

Henry’s Law

 $\mathbf{Solubility}\mathbf{=}{\mathbf{K}}_{\mathbf{H}}\mathbf{\times }{\mathbf{P}}_{\mathbf{gas}}$

$$\begin{gathered} \mathbf{ }\mathbf{ }\mathbf{ }{\mathbf{K}}_{\mathbf{H}}\mathbf{=}\mathbf{Henry}\mathbf{\text{'}}\mathbf{sLawConstant} \\ {\mathbf{P}}_{\mathbf{gas}}\mathbf{=}\mathbf{PressureofGas} \end{gathered}$$

 As the pressure of $O_2\left(g\right)$  increases, the right amount of the pressure will start to increase in the concentration of the oxygen gas.

 

Step 2: Subpart (b) Effect of Volume on N 2 g .

As the volume of $N_2\left(g\right)$ increases, the solubility of the gas decreases becausethe volume is inversely proportional to the pressure

 

Therefore, as the volume increases,the pressure of the gas decreases, and the concentration of the gas decreases and becomesdiluted.