Question

The solubility of a compound is 2.5 g in 100. mL of aqueous solution at 25°C. If we put 1.12 g of the compound in a 50.-mL volumetric flask at 25°C and add sufficient water to fill it to the 50.-mL mark, what kind of solution do we get-saturated or unsaturated?Explain.

Answer 1

1) Saturated solution. A saturated solution contains the maximum amount of solute dissolved. The solubility of the compound is 2.5 g in 100 mL.

2) Find the concentration (percentage mass by volume) of the saturated solution

`\%=\frac{mass\text{ }in\text{ }grams}{milliliters\text{ }of\text{ }solution}*100`
`\%=\frac{2.5\text{ }g\text{ }}{100\text{ }mL}*100=2.5\%`

The concentration of the saturated solution is 2.5 %.

3) Find the concentration (percentage mass by volume) of the sample

`\%=\frac{1.12\text{ }g}{50.\text{ }mL}*100=2.24\%`

The concentration of the sample (1.12g in 50. mL) is 2.24%. The concentration of the sample is lower than the saturated concentration. So, the solution is unsaturated.

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