Stoichiometry Stoichiometry: Calculations with Chemical Formulas and Equations.
Welcome to STOICHIOMETRY
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Transcript of Welcome to STOICHIOMETRY
Welcome to STOICHIOMETRY
Chocolate Chip Cookies 2.25 cups flour 8 Tbsp butter 0.5 cups shortening 0.75 cups sugar 0.75 cups brown sugar 1 tsp salt 1 tsp baking soda 1 tsp vanilla 0.5 cups Egg Beaters
Chocolate Chip Cookies 2.25 cups flour 8 Tbsp butter 0.5 cups shortening 0.75 cups sugar 0.75 cups brown sugar 1 tsp salt 1 tsp baking soda 1 tsp vanilla 0.5 cups Egg Beaters
How much?
What units?
Of what?
2.25 cups flour + 8 Tbsp butter + 0.5 cups shortening +
0.75 cups sugar + 0.75 cups brown sugar + 1 tsp salt +
1 tsp baking soda + 1 tsp vanilla + 0.5 cups Egg Beaters
(a synthesis reaction)
(177ºC)
1 batch of chocolate chip cookies!
coefficient
unit substance
• 2.25 cups flour• 8 Tbsp butter• 0.5 cups shortening• 0.75 cups sugar• 0.75 cups brown sugar• 1 tsp salt• 1 tsp baking soda• 1 tsp vanilla• 0.5 cups Egg Beaters
For 1 batch: The Egg Beaters I have are close to expiring! I’d like to use the rest of them in this recipe. I have 1.5 cups of Egg Beaters.
How many batches of cookies can I make with that many Egg Beaters?
Let’s Revisit the Cookies…
• 2.25 cups flour• 8 Tbsp butter• 0.5 cups shortening• 0.75 cups sugar• 0.75 cups brown sugar• 1 tsp salt• 1 tsp baking soda• 1 tsp vanilla• 0.5 cups Egg Beaters
For 1 batch: I have 1.5 cups of Egg Beaters.
How many batches of cookies can I make with that many Egg Beaters?
=
3.0 batches of cookies
1.5 cups E.B.
.5 cups E.B.
1 Batch
What is Stoichiometry? The study of quantitative relationships
within chemical reactions A balanced equation is the key to
stoichiometry! Tools you’ll need for this chapter:
Writing proper formulas and balanced reactions
Converting from mass to moles and vice versa
Determining the Mole-Ratio
Mole-Ratio Indicated by the coefficients in a balanced
equation
What is the mole-ratio between Mg and MgO?2 mol Mg
2 mol MgO
22 Mg + O Mg + O22 22 MgO MgO
Examples of Mole-Ratios
2KClO3 2KCl + 3O2
What is the mole-ratio of KClO3 and KCl?
2 moles KClO3
2 moles KClWhat is the mole-ratio of KClO3 and O2?
2 moles KClO3
3 moles O2
Another Example
Cu + 2AgNO3 2Ag + Cu(NO3)2
What is the mole ratio for silver nitrate and silver?2 moles AgNO3
2 moles Ag
What is the mole ratio for copper and silver nitrate? 1 mole of Cu
2 moles of AgNO3
Conversion Chart
Molar Mass(g/mol)
6.02 1023
particles/mol
MASSIN
GRAMSMOLES
NUMBEROF
PARTICLES
LITERSOF
SOLUTION
Molarity (mol/L)
The Mole-Mole Ratio is the core step!!
Stoichiometric Calculations
There are three types of stoichiometry problems we will deal with today:Mole-Mole problemsMass-Mole problemsMass-Mass problems
Step 1: Write a BALANCED EQUATION
Step 2: Determine known & unknowns
Step 3: Set up the mole ratio from the coefficients in the equation.
Step 4: Set up the problem like a unit conversion and solve!
Mole-Mole Problems
Mole-Mole ProblemsExample:
2 H2 + O2 2 H2O
How many moles of water can be formed from 0.5 mol H2?
= 0.5 mol H2O.5 mol H2
2 mol H2
2 mol H2O
Mole-Mole PracticeCuSO4 Al Al2(SO4)3 Cu3 2 3+ +
0.5 mol Al 3 mol CuSO4
2 mol Al= 0.75 mol CuSO4
Mole ratio
How many moles of CuSO4 are required to react with .5 moles of Al?
How many moles of Al2(SO4)3 are produced from .5 moles of Al?
0.5 mol Al 1 mol Al2(SO4)3
2 mol Al= .25 mol Al2(SO4)3
Mole ratio
Mole-Mole Practice
2.5 mol Ca 2 mol AlCl3
3 mol Ca= 1.7 mol AlCl3
2.5 mol Ca 3 mol CaCl2
3 mol Ca= 2.5 mol CaCl2
Ca AlCl3 CaCl2 Al3 2 2+ +3
How many moles of AlCl3 are required to react with 2.5 moles of Ca?
How many moles of CaCl2 are produced from 2.5 moles of Ca?
Mass-Mole Problems Step 1: Write a BALANCED EQUATION
Step 2: Determine your known & unknowns
Step 3: Convert known mass to moles (molar mass-known)
Step 4: Convert known mole to unknown mole (Mole-Mole ratio)
Mass-Mole ProblemsExample:
2 H2 + O22 H2O
How many moles of water can be formed from 48.0 g O2?
48.0 g O2
1 mol O2
2 mol H2O = 3.00 mol H2O
32.00 g O2
1 mol O2
Mass-Mole PracticeCuSO4 Al Al2(SO4)3 Cu3 2 3+ +
13.5 g Al 1 mol Al
26.98 g Al= 0.751 mol
CuSO4
13.5 g Al 1 mol Al2(SO4)3
2 mol Al= 0.250 mol
Al2(SO4)3
Mole ratio
3 mol CuSO4
2 mol Al
1 mol Al
26.98 g Al
How many moles of CuSO4 are required to react with 13.5 g of Al?
How many moles of Al2(SO4)3 are produced when 13.5g of Al react?
Mass-Mole Practice
5.7 g Ca 2 mol AlCl3
3 mol Ca= 0.095 mol AlCl3
5.7 g Ca 3 mol CaCl2
3 mol Ca= 0.14 mol CaCl2
Ca AlCl3 CaCl2 Al3 2 2+ +
1 mol Ca
40.08 g Ca
1 mol Ca
40.08 g Ca
3
How many moles of AlCl3 are required to react with 5.7g of Ca?
How many moles of CaCl2 are produced when 5.7g of Ca react?
Mass-Mass Problems Step 1: Write a BALANCED EQUATION
Step 2: Determine your known & unknowns
Step 3: Convert known mass to moles (molar mass-known)
Step 4: Convert known mole to unknown mole (Mole-Mole ratio)
Step 5: Convert unknown mole to gram (molar mass- unknown)
Mass-Mass ProblemsExample:
2 H2 + O22 H2O
How many grams of water can be formed from 48.0 g O2?
48.0 g O2
1 mol O2
2 mol H2O =32.00 g O2
1 mol O2 18.02 g H2O
1 mol H2O54.1 g H2O
Mass-Mass PracticeCuSO4 Al Al2(SO4)3 Cu3 2 3+ +
8.5 g Al 1 mol Al
26.98 g Al=
75 g CuSO4
8.5 g Al 1 mol Al2(SO4)3
2 mol Al=
54 g Al2(SO4)3
Mole ratio
3 mol CuSO4
2 mol Al
1 mol Al
26.98 g Al
1 mol CuSO4
342.14 g Al2(SO4)3
1 mol Al2(SO4)3
159.61 g CuSO4
How many grams of CuSO4 are required to react with 8.5g Al?
How many grams of Al2(SO4)3 are produced when 8.5g Al react?
Mass-Mass Practice
1.9 g Ca 2 mol AlCl3
3 mol Ca=
4.2 g AlCl3
1.9 g Ca 3 mol CaCl2
3 mol Ca=
5.3 g CaCl2
Ca AlCl3 CaCl2 Al3 2 2+ +
1 mol Ca
40.08 g Ca
1 mol Ca
40.08 g Ca
133.33 g AlCl3
1 mol AlCl3
1 mol CaCl2
110.98 g CaCl2
3
What mass of AlCl3 is required to react with 1.9g of Ca?
What mass of CaCl2 is produced when 1.9g of Ca react?