Question

what is the mass percent of carbon in oxalic acid, h₂c₂o₄?
a. 2.24

b. 13.3

c. 26.7

d. 34.5

e. 76

clear my choice

Explanation:

Step1: Calculate molar mass of \(H_2C_2O_4\)

Molar mass of \(H\) is \(1\space g/mol\), \(C\) is \(12\space g/mol\), \(O\) is \(16\space g/mol\).
Molar mass of \(H_2C_2O_4 = 2\times1 + 2\times12 + 4\times16\)
\(= 2 + 24 + 64 = 90\space g/mol\)

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

There are 2 \(C\) atoms, so mass of \(C = 2\times12 = 24\space g/mol\)

Step3: Calculate mass percent of \(C\)

Mass percent formula: \(\frac{\text{Mass of }C}{\text{Molar mass of }H_2C_2O_4}\times100\)
\(=\frac{24}{90}\times100 \approx 26.7\%\)

Answer:

c. 26.7