Question

Calculate the percentage by mass of the indicated element in the following compounds.
Carbon in acetylene, C2H2 , a gas used in welding.
Express your answer using three significant figures.

Answer 1

Answer: The mass percent of carbon in acetylene is 92.31 %.

Explanation:

In $C_2H_2$, there are 2 carbon atoms and 2 hydrogen atoms.

To calculate the mass percent of element in a given compound, we use the formula:

$\text{Mass percent of carbon}=\frac{\text{Mass of carbon}}{\text{Molar mass of acetylene}}\times 100$

Mass of carbon = $2\times 12g/mol=24g$

Mass of acetylene = $2\times 12g/mol+2\times 1g/mol=26g$

Putting values in above equation, we get:-

$\text{Mass percent of carbon}=\frac{24}{26}\times 100=92.31\%$

Hence, the mass percent of carbon in acetylene is 92.31 %.