lecture 12.2a- mol-mol stoich

Bellwork- Simple StoichH2O2(aq) H2O(l) + O2(g)1. Balance the equation2. How many moles of H2O2 must decompose in order to get 2 moles of O2(g)?

3. How many liters of O2(g) are formed from the decomposition of 2 moles of H2O2 at STP? 4. Which are conserved in this reaction- Atoms, molecules, volume, moles, mass?

If given a quantity for one compound in a balanced equation you can calculate quantities for all of the others using stoichiometry.

Example- 2 moles of N2 requires ____moles of H2 and will produce ____moles of NH3.

N2(g) + 3H2(g) 2NH3(g) Reactant #1 Reactant #2 Product

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A mole ratio is a conversion factor made with the coefficients of a balanced chemical equation.

N2(g) + 3H2(g) 2NH3(g)

A mole ratio is a conversion factor made with the coefficients of a balanced chemical equation.

N2(g) + 3H2(g) 2NH3(g)

Some mole ratios: 1 mole N2 3 moles H2 1 mole N2

3 moles H2 1 mole N2 2 mol NH3

N2(g) + 3H2(g) 2NH3(g)

Some mole ratios: 1 mole N2 3 moles H2 1 mole N2

3 moles H2 1 mole N2 2 mol NH3

Use a mole ratio to convert between two different compounds in a balanced equation!

STOICHIOMETRY1) You need a balanced equation.2) Convert the given quantity to

moles if needed.3) Convert moles of given

compound to moles of another compound by using the mole ratio from the balanced equation.

4) Convert moles to grams if needed

N2 + 3H2 2NH3

.6mol N2 x ________ 1mol N2

2mol NH3 = 1.2mol NH3

These numbers come from the balanced equation

for Sample Problem 12.2

For Stoichiometry–

1.You ALWAYS use moles!! If you are not given moles you must convert to moles.

2.Use the mole ratio to convert between compounds.

1. How many moles of water are produced when 2.5 mol of O2 react according to the following equation?

C3H8 + 5O2 3CO2 + 4H2O

a. 2.0

b. 2.5

c. 3.0

d. 4.0