Transcript Bell Ringer

Bell Ringer
Aluminum + Sulfuric Acid 
Aluminum Sulfate + Hydrogen Gas
Which of the following is the
balanced chemical equation
for the reaction shown
above?
A
Al + H2SO4  Al2(SO4)3 + H2
B
2Al + 3H2SO4  Al2(SO4)3 + 3H2
C
2Al + 3H2SO4  Al2(SO4)3 + H2
D
2Al + H2SO4  Al2(SO4)3 + H2
2004 SOL
Chocolate Chip Cookies
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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
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How much? •
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2.25
8
0.5
0.75
0.75
1
1
1
0.5
cups
Tbsp
cups
cups
cups
tsp
tsp
tsp
cups
flour
butter
shortening
sugar
brown sugar
salt
baking soda
vanilla
Egg Beaters
What units?
Of what?
Chocolate Chip Cookies
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How much? •
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2.25
8
0.5
0.75
0.75
1
1
1
0.5
flour
butter
shortening
sugar
brown sugar
salt
baking soda
vanilla
Egg Beaters
Of what?
Chocolate Chip Cookies
•
•
•
How much? •
•
•
•
•
•
2.25
8
0.5
0.75
0.75
1
1
1
0.5
cups
Tbsp
cups
cups
cups
tsp
tsp
tsp
cups
What units?
Chocolate Chip Cookies
•
•
•
How much? •
•
•
•
•
•
2.25
8
0.5
0.75
0.75
1
1
1
0.5
cups
Tbsp
cups
cups
cups
tsp
tsp
tsp
cups
flour
butter
shortening
sugar
brown sugar
salt
baking soda
vanilla
Egg Beaters
What units?
Of what?
Get on with it!
What does this have to do with
CHEMISTRY?
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
unit
coefficient
substance
(177ºC)
1 batch of chocolate chip cookies!
(a synthesis reaction)
Welcome to
STOICHIOMETRY
Ms. Besal
2/23/2006
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
Let’s Revisit the Cookies…
For 1 batch:
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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
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…
For 1 batch:
•
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•
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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
I have 1.5 cups of Egg Beaters.
How many batches of cookies
can I make with that many
Egg Beaters?
1.5 cups E.B.
x
1 batch cookies
0.5 cups E.B.
3.0 batches of cookies
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Let’s Revisit the Cookies…
For 1 batch:
•
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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
I have 1.5 cups of Egg Beaters.
How much butter do I need to
deplete (use up) the Egg
Beaters?
1.5 cups E.B.
x
8 Tbsp butter
0.5 cups E.B.
24 Tablespoons of butter
=
… Back to Chemistry
• There are three types of stoichiometry
problems we will deal with today:
– Mole-Mole problems (1 conversion)
– Mass-Mole problems (2 conversions)
– Mass-Mass problems (3 conversions)
given
required
Baby Steps…
Mole-Mole Problems
• Step 1: Write a BALANCED EQUATION
• Step 2: Determine the mole ratio from the
coefficients in the equation.
– Mole ratio = moles of required substance
moles of given substance
• Step 3: Set up the problem like a unit
conversion and solve!
Mole-Mole Problems
Example:
2 H2 +
O2
2 H2 O
How many moles of water can be formed from 0.5 mol H2?
0.5 mol H2 x 2 mol H2O = 0.5 mol H2O
2 mol H2
Mole-Mole Practice
3 CuSO4 + 2 Al
1. a.
0.5 mol Al
x
Al2(SO4)3 + 3 Cu
Mole ratio
3 mol CuSO4
= 0.8 mol CuSO4
2 mol Al
b. 0.5 mol Al
x
1 mol Al2(SO4)3
= 0.3 mol Al2(SO4)3
2 mol Al
c.
0.5 mol Al
x
3 mol Cu
2 mol Al
= 0.8 mol Cu
Mole-Mole Practice
3 Ca + 2 AlCl3
2. a.
2.5 mol Ca x
3 CaCl2 + 2 Al
2 mol AlCl3
= 1.7 mol AlCl3
3 mol Ca
b. 2.5 mol Ca x
3 mol CaCl2
= 2.5 mol CaCl2
3 mol Ca
c.
2.5 mol Ca x
2 mol Al
3 mol Ca
= 1.7 mol Al
Mass-Mole Problems
• Step 1: Write a BALANCED EQUATION
• Step 2: Calculate the molar mass of your given
substance and convert from mass to moles
• Step 3: Determine the mole ratio from the coefficients
in the equation
• Step 4: Set up the conversion and solve!
Mass-Mole Problems
Example:
2 H2 +
O2
2 H2 O
How many moles of water can be formed from 48.0 g O2?
48.0 g O2 x 1 mol O2 x 2 mol H2O = 3.00 mol H2O
32.00 g O2
1 mol O2
Mass-Mole Practice
3 CuSO4 + 2 Al
1. a.
13.5 g Al x 1 mol Al
26.98 g Al
b.
13.5 g Al x 1 mol Al
26.98 g Al
c.
13.5 g Al x
1 mol Al
26.98 g Al
Al2(SO4)3 + 3 Cu
Mole ratio
3 mol CuSO4
x
=
2 mol Al
x 1 mol Al2(SO4)3 =
2 mol Al
x
3 mol Cu
2 mol Al
0.751 mol
CuSO4
0.250 mol
Al2(SO4)3
= 0.751 mol
Cu
Mass-Mole Practice
3 Ca + 2 AlCl3
2. a. 5.7 g Ca x
1 mol Ca
3 CaCl2 + 2 Al
x
40.08 g Ca
2 mol AlCl3
= 0.095 mol AlCl3
3 mol Ca
b. 5.7 g Ca x 1 mol Ca
40.08 g Ca
x
c. 5.7 g Ca x 1 mol Ca
40.08 g Ca
x
3 mol CaCl2
= 0.14 mol CaCl2
3 mol Ca
2 mol Al
3 mol Ca
=
0.095 mol Al
Mass-Mass Problems
Example:
2 H2 +
O2
2 H2 O
How many grams of water can be formed from 48.0 g O2?
48.0 g O2 x 1 mol O2 x 2 mol H2O x 18.02 g H2O = 54.1 g H2O
32.00 g O2
1 mol O2
1 mol H2O
Mass-Mass Practice
3 CuSO4 + 2 Al
Al2(SO4)3 + 3 Cu
Mole ratio
3 mol CuSO4
1. a. 8.5 g Al x 1 mol Al
x
26.98 g Al
2 mol Al
159.61 g CuSO4 =
x
1 mol CuSO4
75 g CuSO4
b. 8.5 g Al x 1 mol Al
x 1 mol Al2(SO4)3 x 342.14 g Al2(SO4)3 =
26.98 g Al
2 mol Al
1 mol Al2(SO4)3
54 g Al2(SO4)3
Mass-Mass Practice
c. 8.5 g Al x
1 mol Al
26.98 g Al
x
3 mol Cu
2 mol Al
x
63.55 g Cu
1 mol Cu
30. g Cu
=
Mass-Mass Practice
3 Ca + 2 AlCl3
2. a. 1.9 g Ca x
1 mol Ca
3 CaCl2 + 2 Al
x
40.08 g Ca
2 mol AlCl3
3 mol Ca
x 133.33 g AlCl3 =
1 mol AlCl3
4.2 g AlCl3
b. 1.9 g Ca x 1 mol Ca
40.08 g Ca
x
3 mol CaCl2
3 mol Ca
x 110.98 g CaCl2
=
1 mol CaCl2
5.3 g CaCl2
Mass-Mass Practice
3 Ca + 2 AlCl3
3 CaCl2 + 2 Al
3 points
c. 1.9 g Ca x 1 mol Ca x
40.08 g Ca
2 points
2 mol Al
3 mol Ca
3 points
For Monday’s Quiz:
• 2 Mass-Mass problems, 10 points each
• Watch for Significant Figures!
• Label EVERYTHING!
x
26.98 g Al
=
1 mol Al
2 points
0.85 g Al