Question

If I want to make 135. kg of NO, and the reaction proceeds in 78.0% yield, how many kilograms of NH3 must I start with in the presence of excess oxygen? this a sample question for my final and i still dont get it. Please someone help!

Answer 1

Start by writing the balanced equation first.
Then work back from the amount of NO you want to make.
Think about the yield this way. When you want 78g, you actually need to make 100 g. So you need to convert 135 g x 100/78. This is the amount of NO you need to make.
Convert this g of NO to moles.
Convert this to moles of NH3 using the balanced chemical reaction.
And convert the moles of NH3 to g of NH3.