Apologia Chemistry Module 05 Review

Front 1

What are three of the most basic types of chemical reactions?

Back 1

decomposition, formation, and combustion reactions.

Front 2

Explain how you go about doing a decomposition reaction equation.

Back 2

All you need to do is look at the chemical formula of the compound, split it up into its individual elements (being careful to recognize which ones are homonuclear diatomics), and then balance the equation.

Front 3

Explain this statement: Chemical equations are just like mathematical equations.

Back 3

Anything you can do to a mathematical equation you can do to a chemical equation. You can add, subtract, multiply, or divide both sides of a chemical equation by any number.

Front 4

Write the chemical equation that describes the decomposition of ethanol. (C^2H^6O)

Hint: Remember, if you need to use a fraction, then you need to also treat the chemical equation like a mathematical equation and do a math function to both sides!

Back 4

2C^2H^6O ----> 4C + 6H^2 + O^2

(If you are not understanding the steps to this, refer to your book for a review. This is VERY important!)

Front 5

Write the balanced chemical equation for the decomposition of SiH^3F

Back 5

2SiH3F -----> 2Si + 3H^2 + F^2

Front 6

It is acceptable to have a fraction of an atom in a chemical equation. True or False?

Back 6

False. You can't split an atom up.... You can only have 0 atoms or 1 atom -- not one half of an atom.

Front 7

Write the chemical equation for the decomposition of phosphorus trihydride.

Back 7

2PH^3 ---> 2P + 3H^2

Front 8

Write the chemical equation for the decomposition of C^12H^23O^11.

Back 8

2C^12H^23O^11 ---> 24C + 23H^2 + 11O^2

Front 9

Is the following chemical equation a decomposition reaction?

CaCO^3 (s) ---> CaO (s) + CO^2 (g)

Back 9

Yes. Chemists consider this a decomposition reaction since it starts with a single compound and breaks it into two different compounds. We will also consider reactions like this to be decomposition reactions. However, when asked to write the equation for a decomposition reaction, always write the equation for the reaction that produces only elements.

Front 10

Formation reactions are really just the opposite of decomposition reactions. True or False?

Back 10

True.

Front 11

Chemists consider any reaction that starts with several reactants and forms a single product to be a formation reaction. True or False?

Back 11

True.... however, just like in a decomposition reaction equation.... write the equation for a reaction that has only elements as its reactants

Front 12

Write the chemical equation for the formation of MgCO^3.

Back 12

2Mg + 2C + 3O^2 ---> 2MgCO^2

Front 13

Write a balanced chemical equation for the formation of KHCO^3.

Back 13

2K + H^2 + 2C + 3O^2 ----> 2KHCO^3

Front 14

True or false? When you burn a metal, it is considered a complete combustion reaction.

Back 14

False. It is a combustion reaction, but it does not fit our definition of a complete combustion reaction, as it does not start with a compound which contains carbon and hydrogen, and it does not produce carbon dioxide and water.

Front 15

What reactor must you have in order to have a complete combustion reaction?

Back 15

oxygen

Front 16

In a complete combustion reaction, what must be produced?

Back 16

carbon dioxide and water

Front 17

A butane pocket lighter works by evaporating and then burning the liquid butane (C^4H^10) stored in it. Write the balanced chemical equation for this complete combustion reaction.

Back 17

2C^4H^10 (g) + 13O^2 (g) ---> 8CO^2 (g) + 10H^2O (g)

Front 18

An automobile uses the energy gained from burning evaporated gasoline in order to run. Write a balanced chemical equation for the combustion of C^8H^18, an important component of gasoline. Include phase symbols in your equation.

Back 18

2C^8H^18 (g) + 25O^2 (g) ---> 16CO^2 (g) + 18H^2O (g)

Front 19

What determines which of the two reactions will result when an incomplete combustion occurs?

Back 19

The amount of oxygen in the area determines which reaction occurs. If there is still a reasonable amount of oxygen around, the first reaction will occur, forming carbon monoxide and water.

If there is a serious shortage of oxygen in the area, the second reaction will occur, forming carbon (which we usually call “soot”) and water.

Front 20

Why is it a dumb idea to stand behind a running car, or to run a car in an enclosed environment?

Back 20

When an automobile runs, it often burns gasoline in a limited supply of oxygen, causing incomplete combustion.
This incomplete combustion produces the poisonous gas carbon monoxide.

Front 21

When were cars first required to be outfitted with catalytic converters?

Back 21

1975

Front 22

True or False? Catalytic converters are more efficient today.... Eliminating all of the poisonous gas that used to be a problem.

Back 22

False. It only eliminates about 90% of the poisonous gas. (and that is if it is operating correctly!) Which is why it is still dumb to stand behind a car that is on or run it in an enclosed space.

Front 23

What are some other sources of carbon monoxide that people need to be concerned about?

Back 23

natural gas furnaces and fireplaces

Front 24

What is an indication that your fireplace is not getting enough oxygen?

Back 24

Soot = carbon. The more soot, the more you have to worry and then you'll need to figure out what is blocking the airflow!

(think: chimney sweep like in Mary Poppins... Not really. But they do still have chimney sweeps. Just without the "cool" outfits...)

Front 25

Carbon monoxide is tasteless, but there is a slight odor. True or False?

Back 25

False. It is tasteless AND odorless, which is why it is a great idea to have carbon monoxide detectors in your home as well as fire alarms.

Front 26

If you cannot see atoms or molecules, how can you count them???

Back 26

This is accomplished by measuring the mass of the sample and determining the types of atoms or molecules in that sample. Those two pieces of information can tell us how many atoms or molecules exist in the sample.

Front 27

On the periodic table, how is atomic mass indicated, and how are the masses arranged on the table?

Back 27

If you look at the atomic masses listed on the chart they will be below the atomic symbol and you will notice that the atomic masses increase as you read the chart from left to right.

Front 28

What is the mass of a nitrogen atom in grams? (1.00 amu = 1.66 x 10{-24} g )

Back 28

2.32 x 10{-23} g

If you have problems with this, refresh the scientific notation concept.

Front 29

What is the mass of a calcium atom in kg? (1.00 amu = 1.66 x 10{-24} g )

Back 29

6.66 amu x 10{-26} kg

Front 30

What is the molecular mass of ChCl^3 in amu?

Back 30

119.5 amu

Front 31

What is the mass of a Si^6F^12O^6 molecule in grams? (1.00 amu = 1.66 x 10{-24} g )

Back 31

8.18 x 10{-22} g

Front 32

What is the mass of a Na^2SO^4 molecule in g? (1.00 amu = 1.66 x 10{-24} g)

Back 32

2.36 x 10{-22} g.

Front 33

If I have 6.02 x 1023 atoms, I have a mole of atoms. Alternatively, if I have 6.02 x 1023 molecules, I have a mole of molecules.
Is this true or false?

Back 33

True. A mole is a unit of measurement, whether you are talking atoms or molecules.

Front 34

An atom's mass in amu tells you how many grams it takes to have one mole of those atoms.
MEMORIZE THIS STATEMENT.

Back 34

An atom's mass in amu tells you how many grams it takes to have one mole of those atoms.
MEMORIZE THIS STATEMENT.

Front 35

A molecule's mass in amu tells you how many grams it takes to have one mole of those molecules.

MEMORIZE THIS STATEMENT.

Back 35

A molecule's mass in amu tells you how many grams it takes to have one mole of those molecules.

MEMORIZE THIS STATEMENT.

Front 36

Once I know the mass of an atom, I know a conversion relationship that relates grams to moles. For another atom, this conversion relationship exists, but the number of grams is different. Is this true or false?

Back 36

True.

Front 37

How many moles of fluorine atoms exist in a 50.0 g sample of fluorine?

Back 37

2.63 moles

Front 38

People are encouraged to limit their table salt (NaCl) intake to 5.000 grams a day. How many moles of NaCl is that?

Back 38

0.0855 moles

Front 39

How many moles of sulfur atoms are in a 50.0-gram sample of sulfur?

Back 39

There are 1.56 moles in the sample.

Front 40

How many moles of glucose (C^6H^12O^6) are in a 1.25 kg sample?

Back 40

There are 6.94 moles in the sample.

Front 41

What is the first step a chemist takes to convert from grams to moles or from moles to grams?

Back 41

Whether a chemist is converting from grams to moles or from moles to grams, the first step is to determine the mass of the molecule or atom involved.

Front 42

A chemist determines that a sample of pure amonia (NH^3) contains 12.331 moles of NH^3. What is the mass of the sample?

Back 42

2.10 x 10{2}g

Front 43

What is the mass of a NO^3 sample if it contains 0.23 moles?

Back 43

The mass is 14 g.

Front 44

What is the relationship between coefficients and moles in a chemical equation?

Back 44

In chemical equations, the coefficients which appear to the left of each substance tell you how many moles of that substance must be used in the chemical equation.

Front 45

True or False? A chemical equation is really a recipe.

Back 45

True.

Front 46

The decomposition of hydrogen peroxide into water and oxygen is described by the following chemical equation:

2H^2O^2 (l) ---> 2H^O (l) + O^2 (g)

If a chemist begins with 2.4 moles of H^2O^2, how many moles of O^2 will be produced?

Back 46

1.2 moles of oxygen gas

Front 47

True or False? In a chemical equation, you need to know everything about the substances in that chemical equation in order to get the correct answer.

Back 47

False. In general, you DON'T have to know everything... usually you can relate any one substance in that equation to any other substance in that equation!

Front 48

If a chemist has 0.234 moles of C^2H^6O, how many moles of carbon will the chemist get by decomposing the sample?

Back 48

0.468 moles of C

Front 49

The mole concept not only allows us to count the number of atoms or molecules that exist in a sample of matter, but it also allows us to predict ........ what???

Back 49

It also allows us to predict the quantities of substances that are produced in a chemical reaction.

Front 50

A chemist obtains a 122.3-mole sample of ammonia (NH^3). If the chemist allows this sample to decompose, how many moles of hydrogen gas will be produced?

Back 50

The answer is 183.5 moles.

Front 51

Can an element undergo a decomposition reaction?

Back 51

Elements cannot undergo decomposition reactions, because elements have nothing to decompose
into.

Front 52

Classify the following reaction as decomposition, formation, complete combustion, or none of these.

C^6H^12O^6 (s) + 6O^2 (g) ----> 6CO^2 (g) + 6H^2O (g)

Back 52

This equation represents a complete combustion reaction, because O^2 is added while CO^2 and H^2O are produced.

Front 53

Classify the following reaction as decomposition, formation, complete combustion, or none of these.

2H^2 (g) + O^2 (g) -----> 2H^2O (l)

Back 53

This equation represents a formation reaction, because 2 elements come together to produce 1 compound.

Front 54

Classify the following reaction as decomposition, formation, complete combustion, or none of these.

NaCl (s) + AgNO^3 (aq) -----> AgCl (s) + NaNO^3 (aq)

Back 54

None of these

Front 55

Classify the following reaction as decomposition, formation, complete combustion, or none of these.

2HBr (l) + Ca(OH)2 (s) -----> 2H^2O (l) + CaBr^2 (aq)

Back 55

None of these

Front 56

Classify the following reaction as decomposition, formation, complete combustion, or none of these.

2NaHPO^4 (s) ------> 2Na (s) + H^2 (g) + 2P (s) + 4O^2 (g)

Back 56

This equation represents a decomposition reaction, because a single compound is breaking down into it elements.

Front 57

Which of the following is not a formation reaction?

a. H^2CO^3 + 2KOH ----> 2H^2O + K^2CO^3

b. CO^2 (g) + H^2O (g) -----> H^2CO^3 (l)

c. 2S (s) + Cl^2 (g) + 5F^2 (g) -----> 2SF^5Cl

Back 57

The only equation that does not represent a formation reaction is (a). The equation for (b) is a formation equation, because it starts with two reactants and makes only one in the end. Remember, reactions do not have to start with elements in order to be formation equations, we just assume they do when we write them ourselves.

Front 58

Which of the following is not a complete combustion equation?

a. 2C^3H^8O + 9O^2 ----> 6CO^2 + 8H^2O

b. H^2CO^3 (s) -----> CO^2 (g) + H^2O (g)

c. CH^4 (g) + 2O^2 (g) ------> CO^2 (g) + 2H^2O (g)

Back 58

The only equation that does not represent complete combustion is (b). The equation in (b) is a decomposition equation. Even though it produces CO^2 and H^2O, it does not have O^2 as a reactant, so it is not combustion.

Front 59

What is the difference between complete combustion and incomplete combustion?

Back 59

Complete combustion produces carbon dioxide and water. Incomplete combustion produces either
carbon monoxide and water or carbon and water.

Front 60

What does a catalytic converter do for an automobile?

Back 60

A catalytic converter converts carbon monoxide produced in an automobile to carbon dioxide, a non-poisonous gas

Front 61

Which has more mass: 100 hydrogen atoms, 4 sulfur atoms, or 1 lanthanum (La) atom?

Back 61

According to the chart, 100 H's would have a mass of 100 x 1.01 = 101 amu; 4 S's would have a mass of 4 x 32.1 = 128.4 amu, and 1 La has a mass of 138.9 amu. Thus 1 La atom has the most mass.

Front 62

What do the following things have in common?

32.1 g of sulfur,
40.1 g of calcium, and
60.1 g of SiO^2

Back 62

All of the samples contain one mole

Front 63

What is Avogadro's Number and what does it represent?

Back 63

Avogadro.s Number is 6.02 x 10^23, and it represents the number of things that are contained in one mole.

Front 64

Why must a chemical reaction be balanced before it can be used in stoichiometry?

Back 64

In stoichiometry, we convert the quantity of one substance in a chemical reaction into the quantity of another substance. Until the equation is balanced, however, it does not properly represent a
chemical reaction, so it is useless until it is balanced.