Theoretical Yield Example If 4.50 g of HCl are reacted with 15.00 g of CaCO3, according to the following balanced chemical equation, calculate the theoretical yield of CO2.

2223 COOHCaClCaCOHCl2 ++→+ 1. Determine the number of moles of one of the products (CO2 in this example) produced if all of each reactant is used up.

22 COmol0616.0

HClmol2COmol1

xHClg5.36HClmol1

xHClg50.4 =

23

2

3

33 COmol1499.0

CaCOmol1COmol1

xCaCOg1.100

CaCOmol1xCaCOg00.15 =

2. Use the smallest number of moles of the product (CO2) from step 1 to calculate the theoretical yield of product (CO2).

22

22 COg71.2

COmol1COg0.44

xCOmol0616.0 =

Note: Since the reactant, HCl, produces the least amount of product, it is the limiting reactant and the other reactant, CaCO3, is in excess.

Percent Yield Example If 2.50 g of CO2 are isolated, after carrying out the above reaction, calculate the percent yield of CO2.

yield%3.92%100xltheoreticaCOg71.2

isolatedCOg50.2

2

2 =

Notes: If you are given a volume for a reactant, you must determine whether you are working with a pure liquid or a solution. You are probably working with a pure liquid if you are given the starting amount of a reagent in volume without a concentration value. In this case, you need to look up the density; volume substance (mL) x density substance (g/mL) = g substance. Then convert to moles via the MM of the substance. You are definitely working with a solution if you are given the starting amount of a reagent in volume and also a concentration value. a. If the concentration value is molarity (M), volume (L) x M (mol/L) = moles. b. Other concentration definitions must also be used appropriately.