Q13.45 P - Chemistry: Molecular Nature Of Matter And Change

Question

For a saturated aqueous solution of each of the following at   and 1atm, will the solubility increase, decrease, or stay the same when the indicated change occurs?

 (a)He(g), decrease T

 (b)RbI(s), increase P

 

Step-by-Step Solution

Answer

1. The solubility of the Helium gas increasesas the temperature of the gas decreases.
2. The solubility of the RbI solid increases as the pressure of the gas increases.

Step 1: Subpart (a) Effect of decreasing Temperature of Helium gas on solubility.

 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 the temperature of Helium decreases, the concentration of the gas increases.

And as the velocity of the solute decreases,the solubility increases.

Step 2: Subpart (b) Effect of increasing Pressure of RbI(s) on solubility.

 According to Henry’s law, as the pressure of the gas increases, the solubility of the solute increases.

Henry’s Law,

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

${\mathbf{P}}_{\mathbf{gas}}\mathbf{=}\mathbf{Pressure} \mathbf{of} \mathbf{Gas}$

${\mathbf{K}}_{\mathbf{H}}\mathbf{=}\mathbf{Henry}\mathbf{\text{'}}\mathbf{s} \mathbf{Law} \mathbf{Constant}$

Therefore, the solubility will increase as the pressure increases.

It is because the increase in pressure on the RbI solid will get it converted into powder form which will make it easily soluble.