Consider the reaction of KOH with H3PO4 to form K3PO4 and H2O. If 5.38 g H3PO4 is reacted with excess KOH and 7.97 g of K3PO4 is ultimately isolated, what is the percent yield for the reaction?

75%

Explanation:

First, the balanced reaction equation must be written out clearly as a guide to solving the problem. The molar masses of H3PO4 and K3PO4 are then calculated as they will be consistently required in solving the problem. The theoretical yield is obtained from the amount of H3PO4 reacted. Since 1 mole of H3PO4 yields 1 mole of K3PO4, 0.05 moles of H3PO4 yields 0.05 moles of K3PO4. The mass of K3PO4 is produced is then the product of 0.05 and it molar mass hence the theoretical yield. The % yield is calculated as shown.

it's c (engineer's do their work with mechanical stuff not on any living being)