Final answer:
The percentage error in the mass of sodium oxide due to using atomic number instead of atomic mass is 38.69%, which is not listed in the provided options, suggesting a mistake in the question or options.
Step-by-step explanation:
The question involves calculating the percentage error in the mass of sodium oxide obtained if the atomic number of sodium is used instead of its atomic mass. The atomic number of sodium is 11, whereas its atomic mass is approximately 22.990 grams per mole. The molecular formula of sodium oxide is Na2O, which means we need two sodium atoms per molecule of sodium oxide. To calculate the mass of sodium oxide, both the atomic masses of sodium and oxygen are needed. For sodium oxide: 2 (22.990 g/mol Na) + 15.999 g/mol O = 61.979 g/mol.
If the atomic number is mistakenly used, then the incorrect molar mass would be calculated as follows: 2 (11 g/mol Na) + 15.999 g/mol O = 37.999 g/mol. The error in the molar mass calculation is: 61.979 g/mol - 37.999 g/mol = 23.980 g/mol.
To find the percentage error: (23.980 g/mol / 61.979 g/mol) x 100% ≈ 38.69%. This is not one of the options provided, implying there may be an error in the question or the options given.