Question #c3471

1 Answer
Ernest Z.
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

"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

"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

"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"

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