1. Stoichiometry

2. STOICHIOMETRY the study of the quantitative relationships that exist in chemical formulas and reactions

3. The key to understanding… The coefficients in a balanced equation give the relative amounts (in moles) of reactants and products.

4. The coefficients represent moles… 2NaCl  2Na + Cl2
There are ____ moles of salt.
There are ____ moles of sodium. 2
There is ____ mole of diatomic Cl. 1

5. Sample Problem
If you start with 50g of salt, how many grams of chlorine are produced when the salt is decomposed?

6. STEPS TO STOICHIOMETRY PROBLEMS

7. Write the balanced equation!
STEP 1
Write the balanced equation!

8. Find the number of moles of the given substance
STEP 2
Find the number of moles of the given substance

9. STEP 3 Use the balanced equation to find the ratio of moles
of given substance to
moles of needed substance

10. STEP 4 Convert moles of needed substance to whatever quantity
is desired

12. Do you think that in the chemistry lab that we always get the amount of product that we calculate?
No way!!

13. % Yield
actual amount of a product expressed as a % of the theoretical amount of that substance

14. Calculated amount from stoichiometry
Percent Yield
Actual amount
of product from the lab
% Yield =
Calculated amount from stoichiometry