Question

The mass % of C in methane (CH4) is?

Answer 1

Answer:

74.87% Carbon

Explanation:

The molecular mass of CH4 is 16.042 g/ mole.

X=(100 × 12.01) / 16.042= 74.87%  

Answer 2

Answer:

$\boxed {\boxed {\sf 74.87 \% \ C}}$

Explanation:

We want to find the mass percent composition of carbon in methane: CH₄

First, we must calculate the gram formula mass, also called the molar mass. Use the values for mass found on the Periodic Table. Look for carbon and hydrogen.

• C: 12.011 g
• H: 1.008 g

There is no subscript after C, so there is just 1 atom. There is a subscript of 4 after H, so there are 4 atoms of hydrogen. We must multiply hydrogen's mass by 4.

• C: 12.011 g
• H₄: 1.008 g * 4= 4.032 g

• CH₄= 12.011 g+ 4.032 g=16.043 g

Calculate the percent composition.

$\frac {mass \ of \ part}{mass \ of \ whole} *100$

The part is the carbon, or 12.011 grams.

The whole is the entire compound, CH₄, or 16.043 grams.

$\frac { 12.011 \ g }{ 16.043 \ g} *100$

$0.748675435*100\\74.8675435$

Let's round to the nearest hundredth. The 7 in the thousandth place tells us to round the 6 to a 7.

$74.87 \% \ C$

The mass percent of carbon is 74.87%