Intro to Stoichiometry

What is stoichiometry?

Stoichiometry – Uses mole ratios from balanced equations and information about one compound to determine information about another compound in the equation.

2 H2 + O2 2 H2O

2

No coefficient = 1

2

For every 2 moles of H2…

1 mole of O2 is needed to react…

and 2 moles of H2O are produced

What do those coefficients really mean?

Q: When will I ever use this? A: Baking!

2 cups of flour + 1 stick of butter 1 dozen cupcakes

You have:4 cups of flour + 3 sticks of butterHow many cupcakes could you make?

General Mole Mole Conversion

Given x

Mole Ratio = Unknown

Amount of given substance in moles

mole unknown mole given

= Amount of unknown substance in moles

Start with the Balanced EquationExample:

If 4.2 mole of H2 reacts completely with O2, how many moles of O2 are needed?

2 H2 + 1 O2 2 H2O

Start with the Balanced EquationExample:

If 1.5 mole of H2 reacts completely, how many moles of H2O are formed?

2 H2 + 1 O2 2 H2O

Practice:How many moles of AgCl will be precipitated if

0.46 mole AgNO3 is reacts with CaCl2?

__ AgNO3 + __ CaCl2 __ AgCl + __ Ca(NO3)2

Step 1: Balance the EquationStep 2: Set up conversion

Practice:How many moles of AgCl will be precipitated if

0.46 mole AgNO3 is reacts with CaCl2?

__ AgNO3 + __ CaCl2 __ AgCl + __ Ca(NO3)2

Step 1: Balance the Equation

Practice:How many moles of AgCl will be precipitated if

0.46 mole AgNO3 reacts with CaCl2?

__ AgNO3 + __ CaCl2 __ AgCl + __ Ca(NO3)2

Step 2: Set up conversion

2 1 2 1

__H₂SO₄+ ___NaOH→ ___Na₂SO₄+ ___H₂0

1. How many moles of water will be produced if there are 10 moles of sodium hydroxide?

2. How many moles of sulfuric acid are required if 135 moles of sodium sulfate must be produced?

3. How many moles of sodium hydroxide must be available to produce 17 moles of sodium sulfate?

2 H2 + 1 O2 2 H2O

Moles Grams Conversion

Example:If 1.5 mole of H2 reacts completely, how many grams

of H2O are formed?

2 H2 + 1 O2 2 H2O

Moles Grams Conversion

Example:If 5.1 mole of H2 reacts completely with O2, how many

grams of O2 are needed?

Moles Grams ConversionPractice:

How many grams of AgCl will be precipitated if 0.46 mole AgNO3 reacts with CaCl2?

Gram to Gram CalculationsGiven Conversion Mole Ratio Conversion Unknown

Mass of given substance(grams)

X 1 mole

Molar mass of given

X Mole

unknownMole Given

XMolar mass of

unknown1 mole

= Mass of unknown substance

Gram to Gram Calculation 1H₂SO₄+ 2NaOH→ 1Na₂SO₄+ 2H₂0

If 600 grams of sodium sulfate are required, how many grams of sodium hydroxide must be used?

Gram to Gram Calculation 1H₂SO₄+ 2NaOH→ 1Na₂SO₄+ 2H₂0

• If 325 grams of sodium sulfate are required, how many grams of sulfuric acid must be used?

17

Gram to Gram Calculation 1H₂SO₄+ 2NaOH→ 1Na₂SO₄+ 2H₂0

• If 540 grams of sodium hydroxide are available, how much sodium sulfate ( in grams) will be produced?

18

Gram to Gram Calculation 1H₂SO₄+ 2NaOH→ 1Na₂SO₄+ 2H₂0

• If 540 grams of sodium hydroxide are available, how many grams of sulfuric acid must be used?

19