A chemist reacts 8.85 g of iron with an excess of hydrogen chloride to form hydrogen gas and iron choloride. How do you calcualte the theoretical yield and the percentage yield of hydrogen if .27g H2 are collected.

Answer 1

This is just a twist to the usual stoichiometry problem.
1. Write and balance the equation.
2. Convert g you have (in this case 8.85 g Fe) to moles. moles = grams/atomic mass.
3. Using the coefficients in the balanced equation, convert moles Fe to moles H2.
4. Now convert moles H2 to grams H2. grams = moles x molar mass. This value you have obtained is the THEORETICAL YIELD and the process is a straight stoichiometry problem.
5. Now that you have the theoretical yield, you can calculate the percent yield.
%yield = (actual yield/theoretical yield)*100 = ??
0.27 g H2 is the actual yield.