Bell Ringer

1
Bell Ringer
Please take out a piece of paper and answer the
following question individually When magnesium
metal is burned, it forms MgO. How many moles of
oxygen gas are needed to burn 10 moles of Mg? A
2 B 5 C 10 D 20
Mg
O2
MgO

VA Chemistry SOL 2003
2
Homework Answers

• Fill in the Blanks
• quantitative
• reactant
• coefficient
• conservation
• is
• coefficients

• Word Problems
• 0.72 mol HCl
• 1.0 mol HNO3
• 0.19 mol CO2
• 0.19 mol Al
• 180 g I2
• 730 g Cl2
• 7200 g NaCl
• 150,000 g Zn

9. 3.3 g H2 10. 1700 g H2O 11. 10 g H2 12.
700 g CO2 500 g O2
3
Chemistry Key Words

• When a substance is
• Reacted
• Oxidized
• Reduced
• Needed
• Electrolyzed
• IT IS A REACTANT!

• When a substance is
• Formed
• Produced
• Liberated
• Created
• Prepared
• IT IS A PRODUCT!

4
Chemistry Intuition
How many moles of oxygen are liberated by the
electrolysis of 3 moles of water?
electricity
O2
H2O
?

H2
NaOH

H2O
NaCl
HCl

?
HOH
5
Chemistry Intuition
How much zinc is necessary to create 15 grams of
zinc oxide?
Zn
ZnO
?
O2

Fe
Cu

Fe2O3
?
CuO

6
For Todays Quiz
Ca
AlCl3
CaCl2
Al


3
2 mol Al
1 mol Ca
26.98 g Al
c.
1.9 g Ca
x
x

x
3 mol Ca
40.08 g Ca
1 mol Al
0.85 g Al

• For Todays Quiz
• 2 Mass-Mass word problems, 10 points each
• Watch for Significant Figures!
• Label EVERYTHING!

7
Stoichiometry in 3-D!

• We have already learned about these three types
  of conversions
• Mole-Mole
• Mass-Mole
• Mass-Mass

• There are three more types of stoichiometry
  problems we will deal with today for gases
• Mass-Volume
• Volume-Mass
• Volume-Volume

8
Mass-Volume Problems

• Step 1 Write a BALANCED EQUATION
• Step 2 Convert given substance from mass to
  moles
• Step 3 Determine the mole ratio from the
  coefficients in the equation and convert from
  moles of given to moles of required substance
• Step 4 Convert the required substance from moles
  to volume in liters

1 mol 22.4 Liters
9
Mass-Volume Problems
Example
2 H2O
2 H2 O2
How many liters of oxygen are necessary to create
48.0 g H2O?
48.0 g H2O
1 mol O2
1 mol H2O
22.4 L O2
29.8 L O2
x

x
x
2 mol H2O
18.02 g H2O
1 mol O2
10
Volume-Mass Problems

• Step 1 Write a BALANCED EQUATION
• Step 2 Convert given substance from volume in
  liters to moles
• Step 3 Determine the mole ratio from the
  coefficients in the equation and convert from
  moles of given to moles of required substance
• Step 4 Convert the required substance from moles
  to mass in grams using the Periodic Table

11
Volume-Mass Problems
Example
2 H2O
2 H2 O2
How many grams of water are formed by reacting
36.0 L O2?
36.0 L O2
2 mol H2O
1 mol O2
18.02 g H2O
58.7 g H2O
x

x
x
1 mol O2
22.4L O2
1 mol H2O
12
Volume-Volume Problems

• Step 1 Write a BALANCED EQUATION
• Step 2 Convert given substance from volume in
  liters to moles
• Step 3 Determine the mole ratio from the
  coefficients in the equation and convert from
  moles of given to moles of required substance
• Step 4 Convert the required substance from moles
  to volume in liters

1 mol 22.4 Liters
13
Volume-Volume Problems
Example
2 H2O
2 H2 O2
How many liters of H2 are required to react with
5.0 L O2?
5.0 L O2
2 mol H2
1 mol O2
22.4 L H2
10. L H2
x

x
x
1 mol O2
22.4 L O2
1 mol H2
14
Practice Problems
2 H2O (g)
2 H2 (g)
O2 (g)

1 mol H2O
2 mol H2
22.4 L H2
1. a.
63.07 g H2O

x
x
x
18.02 g H2O
2 mol H2O
1 mol H2
78.40 L H2
15
Practice Problems
2 H2O (g)
2 H2 (g)
O2 (g)

1 mol H2O
2 mol H2
22.4 L H2
39.2 L H2O
2. a.

x
x
x
22.4 L H2O
2 mol H2O
1 mol H2
39.2 g H2
16
Practice Problems
2 C2H6 (g)
4 CO2 (g)
6 H2O (g)


7 O2
1 mol O2
4 mol CO2
22.4 L CO2
3. a.
16.0 g O2

x
x
x
32.00 g O2
7 mol O2
1 mol CO2
6.40 L CO2
b.
17
Practice Problems
2 C2H6 (g)
4 CO2 (g)
6 H2O (g)


7 O2
1 mol O2
4 mol CO2
22.4 L CO2
4. a.
5.8 L O2

x
x
x
22.4 L O2
7 mol O2
1 mol CO2
3.3 L CO2
b.
18
For Wednesdays Quiz

• 2 word problems, 10 points each
• mass-volume, volume-mass, volume-volume
• Be aware of
• Significant figures
• LABELS! Pay attention to the labels given in
  the problem! LABEL EVERYTHING!
• Formulas and equation writing