Bell RingerPlease 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 20VA Chemistry SOL 2003

Mg O2 MgO+ 22

10 mol Mg x2 mol Mg

1 mol O2 = 5 mol O2

Homework AnswersFill in the Blanks:

• quantitative

• reactant

• coefficient

• conservation

• is

• coefficients

Word Problems:

1. 0.72 mol HCl

2. 1.0 mol HNO3

3. 0.19 mol CO2

4. 0.19 mol Al

5. 180 g I2

6. 730 g Cl2

7. 7200 g NaCl

8. 150,000 g Zn

9. 3.3 g H2

10. 1700 g H2O

11. 10 g H2

12. 700 g CO2

500 g O2

Chemistry Key WordsWhen 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!

Chemistry Intuition

How many moles of oxygen are liberated by the electrolysis of 3 moles of water?

O2H2O ?+electricity

H22 2

NaOH

How many grams of sodium hydroxide are formed from the reaction of sodium chloride and water?

+ H2ONaCl HCl+ ?HOH

Calculate the amount of iron liberated when copper (II) reacts with ferric oxide.

How much zinc is necessary to create 15 grams of zinc oxide?

Chemistry Intuition

Zn ZnO?O2+ 22

FeCu + Fe2O3 ?CuO+ 323

c. 1.9 g Ca 2 mol Al

3 mol Ca=x

0.85 g Al

x1 mol Ca

40.08 g Ca 1 mol Al

26.98 g Alx

For Today’s Quiz:

• 2 Mass-Mass word problems, 10 points each

• Watch for Significant Figures!

• Label EVERYTHING!

Ca AlCl3 CaCl2 Al3 2 2+ +

3 points

2 points 3 points 2 points

3

For Today’s Quiz:

Stoichiometry in 3-D!

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

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

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

Example:

2 H2 + O22 H2O

48.0 g H2O x2 mol H2O

1 mol O2 =18.02 g H2O

1 mol H2O x x22.4 L O2

1 mol O2

Mass-Volume Problems

How many liters of oxygen are necessary to create 48.0 g H2O?

29.8 L O2

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

Example:

2 H2 + O22 H2O

36.0 L O2 x1 mol O2

2 mol H2O =22.4L O2

1 mol O2 x x18.02 g H2O

1 mol H2O

Volume-Mass Problems

How many grams of water are formed by reacting 36.0 L O2?

58.7 g H2O

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

Example:

2 H2 + O22 H2O

5.0 L O2 x1 mol O2

2 mol H2 =22.4 L O2

1 mol O2 x x22.4 L H2

1 mol H2

Volume-Volume Problems

How many liters of H2 are required to react with 5.0 L O2?

10. L H2

Practice Problems2 H2O (g) 2 H2 (g) O2 (g)+

1. a. 63.07 g H2O 1 mol H2O

18.02 g H2O=x

78.40 L H2

Mole ratio

x2 mol H2

2 mol H2O 1 mol H2

x

b. 63.07 g H2O 1 mol O2

2 mol H2O=x

39.20 L O2

1 mol H2O

18.02 g H2Ox 22.4 L O2

1 mol O2

x

22.4 L H2

Practice Problems2 H2O (g) 2 H2 (g) O2 (g)+

39.2 L H2O 1 mol H2O

22.4 L H2O=x

39.2 g H2

Mole ratio

x2 mol H2

2 mol H2O 1 mol H2

x

b. 39.2 L H2O 1 mol O2

2 mol H2O=x

19.6 g O2

1 mol H2O

22.4 L H2Ox 22.4 L O2

1 mol O2

x

22.4 L H22. a.

2 C2H6 (g) 4 CO2 (g) 6 H2O (g)+

3. a. 16.0 g O21 mol O2

32.00 g O2

=x

6.40 L CO2

Mole ratio

x4 mol CO2

7 mol O2 1 mol CO2

x

b. 16.0 g O26 mol H2O

7 mol O2

=x

9.60 L H2O

1 mol O2

32.00 g O2

x 22.4 L H2O

1 mol H2Ox

22.4 L CO2

+ 7 O2

Practice Problems

Practice Problems2 C2H6 (g) 4 CO2 (g) 6 H2O (g)+

4. a. 5.8 L O21 mol O2

22.4 L O2

=x

3.3 L CO2

Mole ratio

x4 mol CO2

7 mol O2 1 mol CO2

x

b. 5.8 L O26 mol H2O

7 mol O2

=x

5.0 L H2O

1 mol O2

22.4 L O2

x 22.4 L H2O

1 mol H2Ox

22.4 L CO2

+ 7 O2

For Wednesday’s 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