Select the correct answer.

A 520-gram sample of seawater contains 0.317 moles of NaCl. What is the percent composition of NaCl in the water?

A. [tex]1.1\%[/tex]
B. [tex]2.8\%[/tex]
C. [tex]3.6\%[/tex]
D. [tex]6.1\%[/tex]



Answer :

Certainly! Let's analyze and solve the problem step by step.

1. Identify the given quantities:
- Mass of the seawater sample: [tex]\(520 \text{ grams}\)[/tex]
- Moles of NaCl in the sample: [tex]\(0.317 \text{ moles}\)[/tex]
- Molar mass of NaCl: [tex]\(58.44 \text{ g/mol}\)[/tex]

2. Calculate the mass of NaCl in the sample:
We can determine the mass of NaCl by using the relationship:
[tex]\[ \text{Mass of NaCl} = \text{Moles of NaCl} \times \text{Molar mass of NaCl} \][/tex]
Substituting the values:
[tex]\[ \text{Mass of NaCl} = 0.317 \text{ moles} \times 58.44 \text{ g/mol} = 18.52548 \text{ grams} \][/tex]

3. Calculate the percentage composition of NaCl in the seawater:
The percent composition can be calculated with the formula:
[tex]\[ \text{Percent composition of NaCl} = \left( \frac{\text{Mass of NaCl}}{\text{Total mass of the sample}} \right) \times 100 \][/tex]
Substituting the values:
[tex]\[ \text{Percent composition of NaCl} = \left( \frac{18.52548 \text{ grams}}{520 \text{ grams}} \right) \times 100 \approx 3.56\% \][/tex]

After following these steps, we find that the percentage composition of NaCl in the seawater is approximately [tex]\(3.6\%\)[/tex]. Thus, the correct answer is:

C. [tex]\(3.6\%\)[/tex]