How many moles of oxygen gas (O2) are required to completely react with 10 moles of hydrogen gas (H2)?

5 moles of oxygen are required.

Explanation:

Given data:

Moles of O₂ required = ?

Moles of H₂ present = 10 mol

Solution:

Chemical equation:

O₂ + 2H₂       →     2H₂O

Now we will compare the moles of oxygen and hydrogen.

                      H₂        :        O₂

                        2         :         1

                       10         :     1/2×10 = 5 mol

5 moles of oxygen are required.