The balanced equation for the reaction between hydrogen and oxygen to form water is:
2H2 + O2 -> 2H2O
To react 4 moles of hydrogen with 3 moles of oxygen, we will also need 1.5 moles of oxygen.
Since we have enough hydrogen and not enough oxygen to react completely, we can calculate the theoretical yield of water produced.
4 moles of H2 will react to produce 2 moles of H2O and 1.5 moles of O2 will react to produce 0.75 moles of H2O. Therefore, the total theoretical amount of water produced is 2 + 0.75 = 2.75 moles of water.
percent yield = (actual yield / theoretical yield) x 100
percent yield = (3 / 2.75) x 100 = 109.09%.
So the percent yield is 109.09%. This means that 109.09% of the theoretical yield was actually produced, and the reaction was more efficient than expected.
It's worth noting that percent yield can't be more than 100% because it implies that more than the theoretical amount of product was produced, which is not possible. In this case, the percent yield is not a realistic value, therefore, the actual yield and the theoretical yield should be rechecked.