## Percentage Yield HW Question

Science questions not covered in Chem 14A and 14B. Try to limit questions to chemistry (inorganic chemistry, physical chemistry, organic chemistry, biophysical chemistry, biochemistry, materials science, environmental chemistry).

Amanda 3H
Posts: 11
Joined: Wed Sep 18, 2019 12:20 am

### Percentage Yield HW Question

Hi, I'm having trouble solving problem M1 in the homework.

This is the equation given: 2NH3+ClO->N2H4+Cl+H2O. 35g of ammonia and an excess of hypochlorite ions were combined to create 25.2g of hydrazine. What is the percentage yield of hydrazine?

I know that I must divide the mass of each reactant by its molar mass (for example, 35g NH3/17.031g mol NH3), but what is the mass of the "excess" of hypochlorite? How do I solve this without knowing how much of the second reactant is added into the reaction?

PranaviKolla2B
Posts: 114
Joined: Fri Aug 30, 2019 12:17 am

### Re: Percentage Yield HW Question

Since the actual yield depends on the limiting reactant (in this case, the ammonia), we do not need to know the amount of excess reactant (the hypochlorite). First, find how many moles of ammonia are present in 35 grams. Use that to find the proportional amount of hydrazine that should be produced. Then, find the moles of hydrazine present in 25.2 grams. Compare the value that should be produced to the value that was produced.
Divide the theoretical amount by the actual amount and multiply by 100 to find the percentage yield.