Final answer:
In the reaction between hydrogen and oxygen to form water, the percent yield is calculated by dividing the actual yield (3 moles of H₂O) by the theoretical yield (4 moles of H₂O) multiplied by 100, resulting in a 75% yield.
Step-by-step explanation:
The question asks about the percent yield of a chemical reaction where 4 moles of hydrogen (H₂) are reacted with 3 moles of oxygen (O₂) to produce water (H₂O). The balanced chemical equation for the reaction is H₂ + ½ O₂ → H₂O. From stoichiometry, 2 moles of H₂ react with 1 mole of O₂ to produce 2 moles of H₂O.
If we react 4 moles of H₂ with 3 moles of O₂, the limiting reactant will be O₂ since it will not have enough hydrogen to react with all of its moles. Following the stoichiometry of the reaction, 3 moles of O₂ would ideally react with 6 moles of H₂ to form 6 moles of H₂O. However, since only 4 moles of H₂ are available, the maximum yield of H₂O will be 4 moles, as H₂ is the excess reactant. Here, 3 moles of H₂O were actually produced.
Thus, to find the percent yield, we use the formula: Percent yield = (actual yield / theoretical yield) × 100. In this case, the percent yield = (3 moles of H₂O / 4 moles of H₂O) × 100 = 75%. Therefore, the correct answer is b. 75%.