Question

For each of the following solutions, calculate the:

a. grams of$2.0\%(m/m)NaCl$that contains$7.50gofNaCl.$

b. milliliters of$25\%(m/v)NaF$solution that contains$4.0gofNaF.$

c. milliliters of$8.0\%(v/v)$ethanol solution that contains$20.0mL$of ethanol.

Short answer

(part a) $375$grams of $2.0\%(m/m)NaCl$solution containing$7.50gofNaCl.$

(part b) $16$milliliters of $25\%(m/v)NaF$solution containing $4.0gofNaF.$

(part c) $250$milliliters of $8.0\%(v/v)$ethanol solution containing $20.0mL$of ethanol.

Step-by-step solution

Introduction (part a).

Mass proportion is a concentration of solute affirmation which can be estimated of the solution's mass. The formula is given by,

$\text{Mass percentage of solute}=\frac{\text{grams of solute}}{\text{grams of solution}}\times 100\mathrm{\%}$

Given Information (part a).

To determine the number of grammes of solution$2.0\%(m/m)$containing$7.50gofNaCl.$

Explanation (part a).

To determine the grammes, use the equation:

$$\begin{gathered} \text{percentage of solute}=\frac{\text{amountof solute}}{\text{amountof solution}}\times 100\mathrm{\%} \\ 2\mathrm{\%}=\frac{7.50\mathrm{g}}{\text{Amount of solution}}\times 100\mathrm{\%} \\ \mathrm{Amount}\mathrm{of}solution=\frac{7.50\mathrm{g}}{2\%}\times 100\mathrm{\%} \\ =375\mathrm{g} \end{gathered}$$

Given Information (part b).

To determine the volume of the solution in milliliters$25\%(m/v)NaF$solution containing$4.0gofNaF.$

Explanation (part b).

Volume percent formula is:

$\text{percentage of solute}=\frac{\text{amount of solute}}{\text{volume of solution}}\times 100\mathrm{\%}$

$$\begin{gathered} 25\mathrm{\%}=\frac{4.0\mathrm{g}}{\text{volume of solution}}\times 100\mathrm{\%} \\ \mathrm{volume}\mathrm{of}\mathrm{solution}=16\mathrm{mL} \end{gathered}$$

Given Information (part c).

To determine the volume of the solution in milliliters$8.0\%(v/v)$ethanol solution containing$20.0mL$of ethanol.

Explanation (part c).

Volume percent formula is:

$$\begin{gathered} \mathrm{volume}\mathrm{percentage}\mathrm{of}\mathrm{solute}=\frac{\mathrm{volume}\text{of solute}}{\text{volume of solution}}\times 100\mathrm{\%} \\ 8\mathrm{\%}=\frac{20.0\mathrm{ml}}{\text{volume of solution}}\times 100\mathrm{\%} \\ \mathrm{volume}\mathrm{of}\mathrm{solution}=250\mathrm{mL} \end{gathered}$$