Transcript Stoichiometry - Broadneck High School

Stoichiometry
Mole Map
Mass Mountain
Liter Lake
Particle
Peninsula
Mole Island
Using the Mole Map with
Chemical Equations
• We can convert between Moles, Particles
and Grams, but…
• This only gives us information about one
substance!
• How do we determine how much reactants
to use in a chemical reaction? Or how
much product we will create?
STOICHIOMETRY
Proportional Relationships
2 1/4 c. flour
1 tsp. baking soda
1 tsp. salt
1 c. butter
3/4 c. sugar
3/4 c. brown sugar
1 tsp vanilla extract
2 eggs
2 c. chocolate chips
Makes 5 dozen cookies.
I have 5 eggs. How many cookies can I make?
Ratio of eggs to cookies
5 eggs
5 doz.
2 eggs
150 dozen
cookiescookies
= 12.5
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mole Ratio
• A conversion factor that converts moles of
one compound in a balanced chemical
equation into moles of another compound.
2 H2 + O2  2 H2O
• Coefficients tell how many particles (or
MOLES of particles) of each chemical is
needed in the reaction.
Mole Ratios
How many moles of water will be formed if I
react 14.0 moles of oxygen with excess H2?
2 H2 + O2  2 H2O
14.0 moles O2 x 2 moles H2O = 28.0 moles H2O
1 mole O2
MOLE RATIO
From the balanced equation.
Coefficients tell moles of each substance.
Stoichiometry Sea
Known
Unknown
Substance A
Substance B
Mass Mountain
Mass Mountain
Liter Lake
Mole Island
Particle Peninsula
Mole Ratio Mole Island
Raft
Liter Lake
Particle Peninsula
Known
Unknown
Substance A
Substance B
Mass
Volume
Particles
1 mole = 22.4 L @ STP
Mass
Mole
Use coefficients
1 mole
from balanced Mole
chemical equation
= 22.4 L @ STP
Volume
Particles
Stoichiometry Steps
1. Write a balanced equation.
2. Identify known & unknown.
3. Line up conversion factors.
– –Mole
Moleratio
ratio- – Molar mass -
moles
moles
moles
moles
moles  grams
4. Check answer.
Core step in all stoichiometry problems!!
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
How many moles of KClO3 must decompose in
order to produce 9 moles of oxygen gas?
2KClO3  2KCl + 3O2
? mol
x mol KClO3 = 9 mol O2
O2
KClO3
9 mol
2 mol KClO3
3 mol O2
6 mol
= 6 mol KClO3
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Stoichiometry
2 TiO2 + 4 Cl2 + 3 C
115
x gg
x mol
CO2 + 2 CO + 2 TiCl4
4.55 mol
x molecules
How many moles of chlorine will react with 4.55 moles of carbon?
x mol Cl2 = 4.55 mol C
C
4 mol Cl2
3 mol C
= 6.07 mol Cl2
Cl2
How many grams of titanium (IV) oxide will react with 4.55 moles of carbon?
x g TiO2 = 4.55 mol C
C
2 mol TiO2
3 mol C
80 g TiO2
1 mol TiO2
= 243 g TiO2
TiO2
How many molecules of TiCl4 will react with 115 g TiO2?
x molecules TiCl4 = 115 g TiO2
1 mol TiO2 2 mol TiCl4 6.02x1023 molecules TiCl4
1 mol TiCl4
80 g TiO2 2 mol TiO2
= 8.66x1023 molecules TiCl4
TiO2
TiCl4