In a chemical reaction that involves reacting molecules the maximum amount of product formed from the limiting reactant is called the theoretical yield.
In order to calculate the theoretical yield of a chemical reaction we must deal with stoichiometry and have a balanced equation.
First, always make sure to check to see if your chemical equation is balanced.
Unbalanced Chemical Equation
Once you’ve balanced your chemical equation you can start calculations dealing with stoichiometry.
Balanced Chemical Equation
When dealing with stoichiometry you can utilize the stoichiometric chart.
The Stoichiometric Chart
When you are given a balanced equation and information on more than one reactant or starting material you will utilize the stoichiometric chart in order to calculate your theoretical yield.
Let’s Get Started!
The amount of reagents or reactants will be used to determine the maximum amount of product possible.
For example, "If 25.0 g of hydrogen gas reacts with 35.0 g of nitrogen gas to produce ammonia, what is the amount of product (in grams) formed?
Balanced Chemical EquationSTEP 1: Calculate the molecular weights of H2, N2 and NH3 with the atomic masses of the elements taken from the periodic table.
Calculating Molar MassesSTEP 2: Convert the grams of reactants into moles.
Grams to moles conversions
STEP 3: Convert the moles of reactants by doing mole-to-mole comparisons.
Balanced-Chemical-EquationDuring this step we use the coefficients from the balanced equation.
Mole to mole ratio
STEP 4: Convert the moles of product into grams of product.
Moles to grams conversions
STEP 5: Determine the theoretical yield.
By comparing the amounts of product we state that the theoretical yield, sometimes referred to as the 100% yield, represents the smaller amount. Therefore the theoretical yield is 42.6 g NH3.
What’s next?
After determining the theoretical yield of a chemical reaction we can branch out to other stoichiometric operations.
We can calculate percent yield by using theoretical yield and actual yield. In addition we can deal with solution chemistry by relating molarity to mL, L, moles and stoichiometry.
