1. Stoichiometry II

2. Mole Relationships in Equations

3. MOLE- MOLE PROBLEMS

4. Mole-Mole Conversions
How many moles of sodium chloride will be produced if you react 2.6 moles of chlorine gas with an excess (more than you need) of sodium metal?

6. Flowchart Atoms or Molecules Moles Mass (grams) Divide by 6.02 X 1023
Multiply by 6.02 X 1023
Moles
Multiply by atomic/molar mass from periodic table
Divide by atomic/molar mass from periodic table
Mass (grams)

7. Molar Mass of Compounds
Molar mass of CaCl2
Calcium = 40.08g
Chlorine = 35.45g
Molar Mass of calcium chloride = g/mol Ca + (2 X 35.45) g/mol Cl = g/mol CaCl2 20
Ca 
17 Cl 35.45

8. Everything must go through Moles!!!
Calculations
molar mass Grams Moles
Everything must go through Moles!!!

9. Mole-Mass Conversions
2 Na + Cl2  2 NaCl
Most of the time in chemistry, the amounts are given in grams instead of moles
We still go through moles and use the mole ratio, but now we also use molar mass to get to grams
Example: How many grams of chlorine are required to react completely with 5.00 moles of sodium to produce sodium chloride?
5.00 moles Na 1 mol Cl g Cl2
2 mol Na 1 mol Cl2
= 177g Cl2

11. Practice
Calculate the mass in grams of Iodine required to react completely with 0.50 moles of aluminum.

12. Mass-Mole
We can also start with mass and convert to moles of product or another reactant
We use molar mass and the mole ratio to get to moles of the compound of interest
Calculate the number of moles of ethane (C2H6) needed to produce 10.0 g of water
2 C2H6 + 7 O2  4 CO2 + 6 H20
10.0 g H2O 1 mol H2O 2 mol C2H6
18.0 g H2O 6 mol H20
= mol C2H6

13. Mass-Mass Conversions
Most often we are given a starting mass and want to find out the mass of a product we will get (called theoretical yield) or how much of another reactant we need to completely react with it (no leftover ingredients!)
Now we must go from grams to moles, mole ratio, and back to grams of compound we are interested in

14. Mass-Mass Conversion
Ex. Calculate how many grams of ammonia are produced when you react 2.00g of nitrogen with excess hydrogen.
N2 + 3 H2  2 NH3
2.00g N mol N mol NH g NH3
28.02g N2 1 mol N mol NH3
= 2.4 g NH3

15. Guidelines for Reaction Stoichiometry
Write the balanced equation.
Calculate the number of moles of the species for which the mass is given.
Use the coefficients in the equation to convert the moles of
the given substance into moles of the substance desired.
Calculate the mass of the desired species.

17. Practice
Calculate how many moles of oxygen are required to make 10.0 g of aluminum oxide

18. Practice
How many grams of calcium nitride are produced when 2.00 g of calcium reacts with an excess of nitrogen?