Q. 9.40 - An Introduction to General, Organic, and Biological Chemistry

Question

Calculate the mass/volume percent $(m/v)$ for the solute in each of the following:

a. $2.50\mathrm{g}\text{ of }\mathrm{LiCl}$ in $40 mL of \mathrm{LiCl}$ solution.

b. $7.5 \mathrm{g}$ of casein in $20 mL$of low-fat milk.

Step-by-Step Solution

Answer

(part a) The mass/volume percent for the solute 2.50 g in $\text{40 mL of }\mathrm{LiCl}$ solution is $6.25\% (m/v).$

(part b) The mass/volume percent for the solute $7.5 \mathrm{g}$ of casein in$20 mL$ of low-fat milk is $6.25\% (m/v).$

Step 1: Given Information (part a)

The following are the given information to find mass/volume percent:

$2.50\mathrm{g}\text{ of }\mathrm{LiCl}$ in $\text{40 mL of }\mathrm{LiCl}$ solution.

Step 2: Find the mass/volume percent (part a).

The equation for mass volume percent is,

$\text{ Mass }/\text{ volume percent }(\mathrm{m}/\mathrm{v})=\frac{\text{ Mass of solute }}{\text{ Volume of solution }}\times 100$

Substitute the values in equation,

$$\begin{gathered} =\frac{2.50 \mathrm{g}}{40.0 \mathrm{mL}}\times 100 \\ =6.25\% (m/v) LiCl \end{gathered}$$

Step 3: Given Information (part b).

The following are the given information to find mass/volume percent:

$7.5 g$ of casein in $20 mL$ of low-fat milk.

Step 4: Find the mass/volume percent (part b).

The equation for mass volume percent is,

$\text{ Mass }/\text{ volume percent }(\mathrm{m}/\mathrm{v})=\frac{\text{ Mass of solute }}{\text{ Volume of solution }}\times 100$

Substitute the values in equation,

$$\begin{gathered} =\frac{7.5 \mathrm{g}\text{ casein }}{120 \mathrm{mL}\text{ milk }}\times 100\mathrm{\%} \\ =6.25\% (\mathrm{m}/\mathrm{v}) \end{gathered}$$