How many moles of water vapor can be made from 4.9x10^22 molecules H2?

Question

The equation is: 2H2(g)+O2(g)=2H2O(g)

Answer 1

1) Use avogadro's # to convert the # of molecules of H₂ to moles of H₂

1 mole H₂ contains 6.02 x 10²³ molecules H₂

4.9 x 10²² molecules H₂ x (1 mol H₂ / 6.02 x 10²³ molecules H₂) = 0.081 mol H₂

2) From the balanced chemical reaction, 2 moles of H₂ reacts to form 2 moles H₂O. The mole ratio is therefore, 2:2. Use the mole ratio to setup a stoichiometry conversion.

0.081 mol H₂ x (2 mol H₂O / 2 mol H₂) = 0.081 mol H₂O formed