stoichiometry question

Question

2C₂H₂ + 5O₂ → 4CO₂ 2H₂O

How many moles of carbon dioxide are represented?

How many atoms of hydrogen react?

What is the mole ratio between oxygen gas and water?

Answer 1

Carbon dioxide is CO2 and the number in front of that product is 4, so without additional information it is safe to assume we have four moles of carbon dioxide.

As for part b, the only compound that has hydrogen is C2H2 which consists of 2 moles of hydrogen because of the subscript next to the hydrogen. We have 2 moles of C2H2 so we multiply our existing number of moles of hydrogen by 2 to get the total number of moles for hydrogen. Which in this case will be 4 moles.

Oxygen gas is O2 and water is H2O. The coefficient in front of O2 is 5 and the coefficient in front of H2O is 2. So the ratio is 5:2.

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