Stoichiometric calculations

1. Stoichiometric Calculations The coefficients in the balanced equation give the ratio of moles of reactants and products

2. Stoichiometric Calculations From the mass of Substance A you can use the ratio of the coefficients of A and B to calculate the mass of Substance B formed (if it’s a product) or used (if it’s a reactant)

3. Stoichiometric Calculations Starting with 1.00 g of C 6 H 12 O 6 … we calculate the moles of C 6 H 12 O 6 … use the coefficients to find the moles of H 2 O… and then turn the moles of water to grams C 6 H 12 O 6 + 6 O 2  6 CO 2 + 6 H 2 O

4. Sample #1 CH 4 +2O 2 2H 2 O + CO 2 How many moles of CH 4 are needed to make 13 moles of water?

5. Sample #2 CH 4 +2O 2 2H 2 O + CO 2 How many moles of water are made from 10g of Oxygen?

6. Sample #3 CH 4 +2O 2 2H 2 O + CO 2 How many grams of water are produced from 100 moles of CH 4 ?

7. Sample #4 CH 4 +2O 2 2H 2 O + CO 2 How many grams of Oxygen are needed in order to produce 200 g of carbon dioxide?

8. Limiting Reactants The limiting reactant is the reactant present in the smallest stoichiometric amount

9. Limiting Reactants The limiting reactant is the reactant present in the smallest stoichiometric amount In other words, it’s the reactant you’ll run out of first (in this case, the H 2 )

10. Limiting Reactants In the example below, the O 2 would be the excess reagent

11. Theoretical Yield The theoretical yield is the amount of product that can be made In other words it’s the amount of product possible as calculated through the stoichiometry problem This is different from the actual yield, the amount one actually produces and measures

12. Percent Yield A comparison of the amount actually obtained to the amount it was possible to make Actual Yield Theoretical Yield Percent Yield = x 100