Question

Water can be formed in the following reaction:

Answer 1

The  moles  of  oxygen  gas (O2) that is needed is    4  moles

 Explanation

2H2 +O2 → 2H2O

The  moles of O2  is determined using the mole  ratio  of H2:O2

that is from equation  above H2:O2  is 2:1  

If the moles of H2  is 8  moles therefore  the moles  of O2

 = 8 moles x 1/2  = 4 moles