Question

part a
what is the mass percent of carbon in oxalic acid, h₂c₂o₄?
2.24
13.3
26.7
34.5
none of the above

Explanation:

Step1: Calculate molar mass of \(H_2C_2O_4\)

Molar mass of \(H = 1.008\) g/mol, \(C = 12.01\) g/mol, \(O = 16.00\) g/mol.
Molar mass of \(H_2C_2O_4 = 2\times1.008 + 2\times12.01 + 4\times16.00\)
\(= 2.016 + 24.02 + 64.00 = 90.036\) g/mol.

Step2: Calculate mass of C in \(H_2C_2O_4\)

There are 2 C atoms, so mass of C = \(2\times12.01 = 24.02\) g/mol.

Step3: Calculate mass percent of C

Mass percent = \(\frac{\text{Mass of C}}{\text{Molar mass of }H_2C_2O_4} \times 100\)
\(= \frac{24.02}{90.036} \times 100 \approx 26.7\%\).

Answer:

26.7 (corresponding to the option with 26.7)