When hydrogen reacts with oxygen, the product is water. If you produce 36 grams of water from 4 grams of hydrogen, how many grams of oxygen reacted?

Question

When hydrogen reacts with oxygen, the product is water. If you produce 36 grams of water from 4 grams of hydrogen, how many grams of oxygen reacted?

Answer 1

First, write the balanced equation. 

2H2 + O2 ==> 2H2O

36 g H2O x 1 mole/18 g = 2 moles water

4 g H2 x 1 mole/2 g = 2 moles H2

From balanced equation 2 moles H2 reacts with 1 mole O2 to make 2 moles water.

Thus moles of O2 reacted must be 1 mole

1 mole O2 x 32g/mole = 32 g O2