1. Aim: How to do Mass to Mass Calculations

2. Mass to Mass Calculations

3. Example 1 2Mg(s) + O 2 (g)  2MgO(s) 12.2 g of magnesium reacts completely with oxygen gas. Calculate the mass of the oxygen consumed during the reaction.

4. Example 1

6. Step 3: Convert moles of oxygen to mass of oxygen. Mass = mole * molar mass Mass O 2 = 0.251 mol * 32.0 g/mol Mass O 2 = 8.03 g

7. Example 2 How many grams of calcium are needed to react completely with 108 grams of H 2 O in the equation ◦Ca + 2H 2 O  Ca(OH) 2 + H 2

8. Example 2

10. Step 3: Convert from moles to mass. Mass = mole * molar mass Mass Ca = 3.00 mol * 40.1 g/mol Mass Ca = 120 g