Q. 9.44 - An Introduction to General, Organic, and Biological Chemistry

Question

For each of the following solutions, calculate the:

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

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

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

Step-by-Step Solution

Answer

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

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

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

Step1: 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,

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

Step2: Given Information (part a).

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

Step3: Explanation (part a).

To determine the grammes, use the equation:

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

Step4: Given Information (part b).

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

Step5: Explanation (part b).

Volume percent formula is:

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

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

Step6: Given Information (part c).

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

Step7: Explanation (part c).

Volume percent formula is:

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