Question

A 57.6 g sample of methane (CH4) is found to contain 43.2 g of carbon. What is the

percent composition of Carbon and Hydrogen? How much hydrogen (in grams) would a
37.8 g sample of methane contain?

Answer 1

Step-by-step explanation:

• The atomic mass of carbon is 12.011 g/mol.
• The atomic mass of hydrogen is 1.00794 g/mol.

This means that the atomic mass of methane is 12.011+4(1.00794)=16.04276 g/mol.

• The percent composition by mass of carbon is
  `(12.011)/(16.04276) * 100=\boxed{74.9\%}`
• The percent composition by mass of hydrogen is
  `(4(1.00794))/(16.04276) * 100=\boxed{25.1\%}`

This means that in a 37.8-gram sample of methane, there would be
`(37.8)\left((25.1)/(100) \right)=\boxed{9.49}` grams of hydrogen.