What is the percent by mass of sodium (Na) in sodium chloride (NaCl)? Use the atomic masses: Na = 22.99 g/mol, Cl = 35.45 g/mol.

• A. 22.99%
• B. 60.66%
• C. 39.34%
• D. 35.45%

Answer: (C)

Verified step by step guidance

1. Identify the atomic masses of the elements involved: sodium (Na) has an atomic mass of 22.99 g/mol, and chlorine (Cl) has an atomic mass of 35.45 g/mol.
2. Calculate the molar mass of sodium chloride (NaCl) by adding the atomic masses of sodium and chlorine: \(\text{Molar mass of NaCl} = 22.99 + 35.45\) g/mol.
3. Determine the percent by mass of sodium in sodium chloride using the formula: \(\text{Percent by mass of Na} = \left( \frac{\text{Atomic mass of Na}}{\text{Molar mass of NaCl}} \right) \times 100\%\).
4. Substitute the known values into the formula: \(\text{Percent by mass of Na} = \left( \frac{22.99}{22.99 + 35.45} \right) \times 100\%\).
5. Perform the division and multiplication to find the percent by mass of sodium in sodium chloride.