1. MASS TO MASS STOICHIOMETRY

2. MOLE-MASS PROBLEMS  Problem 1: 1.50 mol of KClO 3 decomposes. How many grams of O 2 will be produced? [k = 39, Cl = 35.5, O = 16] 2 KClO 3 2 KCl + 3 O 2

3. THREE STEPS…GET YOUR CORRECT ANSWER  Use your mole ratio equation  Get the answer in moles and then  Convert to Mass. Next: If you are given a mass in the problem, you will need to convert this to moles first

4. LET’S GO! 2 KClO 3 2 KCl + 3 O 2 Convert to mass 2.25 mol x 32.0 g/mol = 72.0 grams

5. TRY THIS:  We want to produce 2.75 mol of KCl. How many grams of KClO 3 would be required?

6. MASS TO MASS  We can use a simple 3 step method to solve stoichiometric questions with balanced equations.  Identify the given and convert it to moles.  Identify the unknown, and multiply the given number of moles by the mole ratio to produce moles of desired substance.  Convert moles of desired substance to the units asked for in the question.

7. EXAMPLE  What mass of methane gas in grams must burn to produce 365 grams of water, by the following chemical reactions ?  Given is 365 g of water. Calculate moles of water.  Identify desired; mass of Methane gas. Multiple by mole ratio _1_CH 4 (g)+_2_O 2 (g)_2_H 2 O (g)+_1_CO 2 (g) 365 g ÷18.02 g/mol=20.25 mol 20.25 mol H 2 O (l)X1 CH 4 (g)=10.13 mol CO 2 (g) 2 H 2 O (g)

8.  Convert moles of desired to the units asked for in the question: Mass of Methane gas.  Assignment: Mass to Mass Stoichiometry 10.13 mol CO2X44.01 g/mol=446 g