Cecil writes the equation for the reaction of hydrogen and oxygen below. H2 + O2 → H2O Why does his teacher ask him to balance the equation by including the correct coefficients?

2H2 + O2 → 2H2O

Explanation:

Step 1: Data given

hydrogen = H2

oxygen = O2

water = H2O

Step 2: The unbalanced equation

H2 + O2 → H2O

Step 3: Balancing the equation

H2 + O2 → H2O

On the left side we have 2x O (in O2), On the right side we have 1x O (in H2O). To balance the amount of O on both sides, we have to multiply H2O (on the right side) by 2

H2 + O2 → 2H2O

On the left side we have 2x H (in H2), On the right side we have 4x H (in 2H2O). To balance the amount of H on both sides, we have to multiply H2 (on the left side) by 2. Now the equation is balanced.

2H2 + O2 → 2H2O

This means for 1 mol oxygen we need 2 moles of H2 to produce 2 moles of H2O