Question

What is the percent by mass of NaCl in a solution that contains 17.5 g NaCl per 500.0 g of water?

a
3.61%
b
14.80%
c
3.50%
d
3.38%

Answer 1

To calculate the percent by mass of NaCl in the solution, you can use the following formula:

\[
\text{Percent by mass} = \left( \frac{\text{mass of solute}}{\text{mass of solute} + \text{mass of solvent}} \right) \times 100
\]

In this case, the mass of the solute (NaCl) is 17.5 g, and the mass of the solvent (water) is 500.0 g.

First, calculate the total mass of the solution:

\[
\text{Total mass of solution} = \text{mass of solute} + \text{mass of solvent} = 17.5 \, \text{g} + 500.0 \, \text{g} = 517.5 \, \text{g}
\]

Next, apply the values to the percent by mass formula:

\[
\text{Percent by mass} = \left( \frac{17.5}{517.5} \right) \times 100
\]

Calculating that gives:

\[
\text{Percent by mass} = 0.0338 \times 100 = 3.38\%
\]

Therefore, the correct answer is:

**d) 3.38%**