Which Is More Soluble?

Chemistry Level 2

25 grams of water can dissolve 5 grams of $X$ at $30^\circ\text{C}.$ A $60\text{ g}$ saturated $Y$ solution contains 10 grams of solute $Y$ at $33^\circ \text{C}$ . Which of the below MUST be true about their solubilities?

s_X=s_Y

s_X>s_Y

s_X<s_Y

Nothing is confirmed true.

1 solution

Anish Puthuraya
Mar 2, 2014

We observe that,
$s_X = \frac{5g}{25g} = 0.2$ $s_Y = \frac{10g}{60g-10g} = 0.2$

So, Both the solutes must have the same solubility, right?

Unfortunately, the answer is NO .

Note that the temperatures are different for both the systems..
Moreover, it is not necessary that the solubility of a solute in a particular solvent must increase with temperature.

Hence, there is nothing that we can say for sure...
The Answer is : Nothing is confirmed true

I am so glad the answer provided for the problem is actually correct. When I picked this answer, I was ready to defend it.

While most substances have higher solubility in solvents at higher temperatures, there are some substances that actually become less soluble at higher temperature. This is because solubility is an equilibrium phenomenon and the change in Gibbs free energy when a substance dissolve in a solvent is affected by both the enthalpy change of solution as well as the change in entropy when the substance dissolve and become solvated.

Tong Choo - 7 years, 3 months ago

I am sure that the answer must be this. To prevent some careless mistake made by others, I purposely emphasis the MUST as a hint. By the way, a good explanation from you and Anish!

Christopher Boo - 7 years, 3 months ago

Thank you..

Anish Puthuraya - 7 years, 3 months ago

Which Is More Soluble?

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