# Question c3471

Sep 24, 2016

How many atoms of hydrogen are in 23.7 g of methane?

There are 3.56 × 10^24color(white)(l) "atoms of H"#.

There are three steps to follow in this problem:

1. Use the molar mass of methane to calculate the moles of methane.
2. Use the molar ratio of hydrogen atoms:methane molecules from the formula to calculate the moles of hydrogen atoms.
3. Use Avogadro's number to calculate the atoms of hydrogen.

1. Calculate the moles of methane

${\text{Moles of CH"_4 = 23.7 color(red)(cancel(color(black)("g CH"_4))) × ("1 mol CH"_4)/(16.04 color(red)(cancel(color(black)("g CH"_4)))) = "1.478 mol CH}}_{4}$

2. Calculate the moles of hydrogen atoms

$\text{Moles of H" = 1.478 color(red)(cancel(color(black)("mol CH"_4))) × ("4 mol H")/(1 color(red)(cancel(color(black)("mol CH"_4)))) = "5.910 mol H}$

3. Finally, calculate the number of atoms

$\text{Atoms of H" = 5.910 color(red)(cancel(color(black)("mol H"))) × (6.022 × 10^23color(white)(l) "atoms H")/(1 color(red)(cancel(color(black)("mol H")))) = 3.56 × 10^24color(white)(l) "atoms H}$