Final answer:
Upon calculating the percent composition by mass of sodium in sodium phosphate, the correct percentage should be about 42%, which is not listed in the provided options. This could indicate an error in the question or the options given.
Step-by-step explanation:
To calculate the percent composition by mass of sodium (Na) in sodium phosphate (Na3PO4), you need to know the molar masses of sodium and the entire compound. The molar mass of sodium (Na) is approximately 22.99 g/mol, and for sodium phosphate (Na3PO4), the molar mass can be calculated by adding together the molar masses of all the atoms present in the formula: 3(22.99) for sodium, 30.97 for phosphorus (P), and 4(16.00) for oxygen (O).
The molar mass of Na3PO4 = 3(22.99) + 30.97 + 4(16.00) = 163.94 g/mol.
The total mass of sodium in the compound is 3(22.99) = 68.97 g.
Next, you use the formula for percent composition:
Percent Composition of Na = (Mass of Na / Molar Mass of Na3PO4) × 100%
= (68.97 g / 163.94 g) × 100% ≈ 42.07%
This is not one of the given options, so we must ensure our calculations were done properly. Upon reviewing, it is clear that the molar mass of sodium phosphate was initially calculated incorrectly. Let's try the calculations again.
The correct molar mass of Na3PO4 = 3(22.99) + 30.97 + 4(16.00) = 163.94 g/mol (which is accurate).
Using the correct mass of sodium, which is 3(22.99) = 68.97 g, the percent composition calculation would be:
Percent Composition of Na = (68.97 g / 163.94 g) × 100% ≈ 42.07%
However, this result still does not match any of the options provided. If we consider rounding to whole numbers, about 42% would be nearer to the correct percentage. This nuanced discrepancy suggests that an error was made in the question or in the options provided.