Question 1

Balance the following chemical equation. ____ N2 + ____ H2 → ____ NH3

Accepted Answer

A) 1, 3, 2 
B) 1, 2, 3 
C) 3, 2, 1 
D) 2, 6, 4 
E) 1/2, 3/2, 1 
A) 1, 3, 2 
B) 1, 2, 3 
C) 3, 2, 1 
D) 2, 6, 4 
E) 1/2, 3/2, 1

Question 2

What are the formula masses of water, H2O; propene, C3H6; and 2-propanol, C3H8O?

Accepted Answer

A) water: 18 amu; propene: 40 amu; 2-propanol: 58 amu 
B) water: 18 amu; propene: 42 amu; 2-propanol: 62 amu 
C) water: 18 amu; propene: 42 amu; 2-propanol: 60 amu 
D) water: 18 amu; propene: 44 amu; 2-propanol: 64 amu 
A) water: 18 amu; propene: 40 amu; 2-propanol: 58 amu 
B) water: 18 amu; propene: 42 amu; 2-propanol: 62 amu 
C) water: 18 amu; propene: 42 amu; 2-propanol: 60 amu 
D) water: 18 amu; propene: 44 amu; 2-propanol: 64 amu

Question 3

If it takes three carbon atoms to equal the mass of one chlorine atom, what weight of chlorine do you need to equal the number of atoms in one kilogram of carbon?

Accepted Answer

A) 1/3 of a kg 
B) 30 kg 
C) 1 kg 
D) 3 kg 
E) 6 kg 
A) 1/3 of a kg 
B) 30 kg 
C) 1 kg 
D) 3 kg 
E) 6 kg

Question 4

Why is it important for a chemist to know the relative masses of atoms?

Accepted Answer

A) There are not that many different kinds of atoms and so it's important to know how they relate to one another. 
B) It provides information about how many atoms two samples have relative to each other 
C) It provides an indication of how the different atoms will interact 
D) Because the mass of an atom is directly related to its chemical properties. 
A) There are not that many different kinds of atoms and so it's important to know how they relate to one another. 
B) It provides information about how many atoms two samples have relative to each other 
C) It provides an indication of how the different atoms will interact 
D) Because the mass of an atom is directly related to its chemical properties.

Question 5

Since some of the compounds that are destroying ozone are found in nature normally, how is it possible to tell that the reactive molecules destroying the ozone are due to our actions?

Accepted Answer

A) They are accompanied by compounds that are only man-made. 
B) The compounds only increased in the past few years. 
C) The isotope distribution is unique to man-made elements. 
D) The chemical composition is different than natural compounds. 
E) all of the above 
A) They are accompanied by compounds that are only man-made. 
B) The compounds only increased in the past few years. 
C) The isotope distribution is unique to man-made elements. 
D) The chemical composition is different than natural compounds. 
E) all of the above

Question 6

An Alka-Seltzer antacid tablet bubbles vigorously when placed in water but only slowly when placed in an alcoholic beverage of the same temperature containing a 50:50 mix of alcohol and water. Propose a probable explanation involving the relationship between the speed of a reaction and molecular collisions.

Accepted Answer

A) The alcohol absorbs the carbon dioxide bubbles before they escape the liquid phase. 
B) Alcohol molecules are more massive than water molecules, hence they move slower and their collisions are not as forceful. 
C) The tablet reacts with water but not the alcohol. 
D) In a 50:50 mix there are fewer water molecules for the antacid molecules to collide with. 
A) The alcohol absorbs the carbon dioxide bubbles before they escape the liquid phase. 
B) Alcohol molecules are more massive than water molecules, hence they move slower and their collisions are not as forceful. 
C) The tablet reacts with water but not the alcohol. 
D) In a 50:50 mix there are fewer water molecules for the antacid molecules to collide with.

Question 7

For the following balanced reaction, which of the following is a gas? 2 Na(l)+ Cl2(g)→ 2 NaCl(s)

Accepted Answer

A) Na 
B) 2 Na 
C) Cl2 
D) Cl 
E) NaCl 
A) Na 
B) 2 Na 
C) Cl2 
D) Cl 
E) NaCl

Question 8

What coefficient is needed in front of the O2 molecule to balance the following equation? 2 C4H10 (g)+ _____ O2 (g)→ 8CO2 (g)+ 10 H2O (l)

Accepted Answer

A) 8 
B) 13 
C) 5 
D) 1 
A) 8 
B) 13 
C) 5 
D) 1

Question 9

What is the formula mass of a molecule of CO2?

Accepted Answer

A) 44 amu 
B) 56 amu 
C) 58.9 amu 
D) 118 amu 
E) none of the above 
A) 44 amu 
B) 56 amu 
C) 58.9 amu 
D) 118 amu 
E) none of the above

Question 10

Given that the above energy profiles have the same scale, which of the reactions is the most exothermic?

Accepted Answer

A) a 
B) b 
C) c 
D) d 
E) none of the above 
A) a 
B) b 
C) c 
D) d 
E) none of the above

Question 11

Why might increasing the temperature alter the rate of a chemical reaction?

Accepted Answer

A) The molecules will have a higher kinetic energy and bump into one another harder. 
B) The molecules are less reactive at higher temperatures. 
C) The molecules will more likely combine with other atoms at high temperature to save space. 
D) The density decreases as a function of temperature and this leads to an increase in volume which drops the rate of reaction. 
E) none of the above 
A) The molecules will have a higher kinetic energy and bump into one another harder. 
B) The molecules are less reactive at higher temperatures. 
C) The molecules will more likely combine with other atoms at high temperature to save space. 
D) The density decreases as a function of temperature and this leads to an increase in volume which drops the rate of reaction. 
E) none of the above

Question 12

Steel wool wetted with vinegar is sealed within a balloon inflated with air. After several hours, what happens to the volume of the balloon?

Accepted Answer

A) The balloon inflates. 
B) The balloon deflates. 
C) The balloon dissolves. 
D) Nothing because the vinegar is acting on the steel wool, not upon the balloon. 
A) The balloon inflates. 
B) The balloon deflates. 
C) The balloon dissolves. 
D) Nothing because the vinegar is acting on the steel wool, not upon the balloon.

Question 13

Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle. A rubber balloon is then sealed over the mouth of the bottle. After several hours, the balloon inflates into the bottle in an inverted manner. What happened?

Accepted Answer

A) Vinegar fumes are diamagnetic and as they accumulate above the liquid the steel wool is attracted thus inflating the balloon into the mouth of the bottle in an inverted manner. 
B) The caustic vinegar fumes get past the steel wool and deteriorate the balloon, which begins to sag into the bottle and inflate it in an inverted manner. 
C) The vinegar reacts with the steel wool by absorbing oxygen within the bottle thus decreasing the pressure. The greater outside pressure causes the balloon to inflate in an inverted manner. 
D) False! The balloon inflates above the mouth of the bottle because the reaction between the vinegar and steel wool produces a gas which is forced upward because of increased pressure inside the sealed bottle. 
A) Vinegar fumes are diamagnetic and as they accumulate above the liquid the steel wool is attracted thus inflating the balloon into the mouth of the bottle in an inverted manner. 
B) The caustic vinegar fumes get past the steel wool and deteriorate the balloon, which begins to sag into the bottle and inflate it in an inverted manner. 
C) The vinegar reacts with the steel wool by absorbing oxygen within the bottle thus decreasing the pressure. The greater outside pressure causes the balloon to inflate in an inverted manner. 
D) False! The balloon inflates above the mouth of the bottle because the reaction between the vinegar and steel wool produces a gas which is forced upward because of increased pressure inside the sealed bottle.

Question 14

Is it possible to have a macroscopic sample of oxygen that has a mass of 14 atomic mass units?

Accepted Answer

A) Yes, but it would need to be made of oxygen atoms that each had less than the normal number of neutrons. 
B) No, this is less than than the mass of a single oxygen atom. 
C) Yes, but it would have the same density as nitrogen. 
D) No, because oxygen is a gas at room temperature. 
A) Yes, but it would need to be made of oxygen atoms that each had less than the normal number of neutrons. 
B) No, this is less than than the mass of a single oxygen atom. 
C) Yes, but it would have the same density as nitrogen. 
D) No, because oxygen is a gas at room temperature.

Question 15

Why is there a drastic reduction in ozone in the spring?

Accepted Answer

A) There is a sudden increase in Cl atoms in the spring. 
B) It is warmer in the spring. 
C) There are more chlorofluorocarbons in the spring. 
D) all of the above 
E) only a and b 
A) There is a sudden increase in Cl atoms in the spring. 
B) It is warmer in the spring. 
C) There are more chlorofluorocarbons in the spring. 
D) all of the above 
E) only a and b

Question 16

If it takes three golf balls to equal the mass of one tennis ball, what mass of tennis balls do you need to equal the number of golf balls in one kilogram of golf balls?

Accepted Answer

A) 1/3 of a kg 
B) 30 kg 
C) 1 kg 
D) 3 kg 
E) 6 kg 
A) 1/3 of a kg 
B) 30 kg 
C) 1 kg 
D) 3 kg 
E) 6 kg

Question 17

Why does iodine, I2 (s), spontaneously sublime at room temperature?

Accepted Answer

A) The contact of iodine, I2 (s), with the water vapor in the air causes the sublimation process. 
B) Iodine, I2 (s), pulls O2 from the air as it self-oxidizes under sublimation to I2 (g). 
C) There is an increase in entropy as solid iodine, I2 (s), sublimes into iodine vapor, I2 (g), because in the gaseous phase energy is more readily dispersed. 
D) The reaction of I2 (s)subliming to I2 (g)is highly exothermic and therefore proceeds spontaneously. 
A) The contact of iodine, I2 (s), with the water vapor in the air causes the sublimation process. 
B) Iodine, I2 (s), pulls O2 from the air as it self-oxidizes under sublimation to I2 (g). 
C) There is an increase in entropy as solid iodine, I2 (s), sublimes into iodine vapor, I2 (g), because in the gaseous phase energy is more readily dispersed. 
D) The reaction of I2 (s)subliming to I2 (g)is highly exothermic and therefore proceeds spontaneously.

Question 18

The relative mass of carbon is 3/8 that of an oxygen molecule. How many grams of carbon are needed to have the same number of particles as found in 32 grams of oxygen molecules?

Accepted Answer

A) 12 g 
B) 32 g 
C) 3 g 
D) 8 g 
E) 3/8 g 
A) 12 g 
B) 32 g 
C) 3 g 
D) 8 g 
E) 3/8 g

Question 19

What is the number of moles of H2O produced if you combust 0.5 mole of CH4 according to the following balanced equation? CH4 + 2 O2 → CO2 + 2 H2O

Accepted Answer

A) 2 moles 
B) 4 moles 
C) 6 moles 
D) 8 moles 
E) 1 mole 
A) 2 moles 
B) 4 moles 
C) 6 moles 
D) 8 moles 
E) 1 mole

Question 20

What is an exothermic reaction?

Accepted Answer

A) It is a reaction that requires heat as a reactant. 
B) It is a reaction where the products have more energy than the reactants. 
C) It is a reaction where there is a net adsorption of energy from a reaction. 
D) all of the above 
E) none of the above 
A) It is a reaction that requires heat as a reactant. 
B) It is a reaction where the products have more energy than the reactants. 
C) It is a reaction where there is a net adsorption of energy from a reaction. 
D) all of the above 
E) none of the above

Exam 17: How Chemicals React

Balance the following chemical equation. ____ N2 + ____ H2 → ____ NH3

What are the formula masses of water, H2O; propene, C3H6; and 2-propanol, C3H8O?

If it takes three carbon atoms to equal the mass of one chlorine atom, what weight of chlorine do you need to equal the number of atoms in one kilogram of carbon?

Why is it important for a chemist to know the relative masses of atoms?

Since some of the compounds that are destroying ozone are found in nature normally, how is it possible to tell that the reactive molecules destroying the ozone are due to our actions?

For the following balanced reaction, which of the following is a gas? 2 Na(l)+ Cl2(g)→ 2 NaCl(s)

What coefficient is needed in front of the O2 molecule to balance the following equation? 2 C4H10 (g)+ _____ O2 (g)→ 8CO2 (g)+ 10 H2O (l)

What is the formula mass of a molecule of CO2?

Given that the above energy profiles have the same scale, which of the reactions is the most exothermic?

Why might increasing the temperature alter the rate of a chemical reaction?

Steel wool wetted with vinegar is sealed within a balloon inflated with air. After several hours, what happens to the volume of the balloon?

Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle. A rubber balloon is then sealed over the mouth of the bottle. After several hours, the balloon inflates into the bottle in an inverted manner. What happened?

Is it possible to have a macroscopic sample of oxygen that has a mass of 14 atomic mass units?

Why is there a drastic reduction in ozone in the spring?

If it takes three golf balls to equal the mass of one tennis ball, what mass of tennis balls do you need to equal the number of golf balls in one kilogram of golf balls?

Why does iodine, I2 (s), spontaneously sublime at room temperature?

The relative mass of carbon is 3/8 that of an oxygen molecule. How many grams of carbon are needed to have the same number of particles as found in 32 grams of oxygen molecules?

What is the number of moles of H2O produced if you combust 0.5 mole of CH4 according to the following balanced equation? CH4 + 2 O2 → CO2 + 2 H2O

What is an exothermic reaction?

Patterns of Motion and Equilibrium

Newtons Laws of Motion

Momentum and Energy

Gravity, Projectiles, and Satellites

Fluid Mechanics

Thermal Energy and Thermodynamics

Heat Transfer and Change of Phase

Static and Current Electricity

Magnetism and Electromagnetic Induction

Waves and Sound

Light

Atoms and the Periodic Table

The Atomic Nucleus and Radioactivity

Elements of Chemistry

How Atoms Bond and Molecules Attract

Mixtures

Two Classes of Chemical Reactions

Organic Compounds

Rocks and Minerals

Plate Tectonics and Earths Interior

Shaping Earths Surface

Geologic Timereading the Rock Record

The Oceans, Atmosphere, and Climatic Effects

Driving Forces of Weather

The Solar System

Stars and Galaxies

The Structure of Space and Time

Prologue: the Nature of Science

Filters

Balance the following chemical equation. N₂ + H₂ → NH₃

What are the formula masses of water, H₂O; propene, C₃H₆; and 2-propanol, C₃H₈O?

For the following balanced reaction, which of the following is a gas? 2 Na(l)+ Cl₂(g)→ 2 NaCl(s)

What coefficient is needed in front of the O₂ molecule to balance the following equation? 2 C₄H₁₀ (g)+ _____ O₂ (g)→ 8CO₂ (g)+ 10 H₂O (l)

What is the formula mass of a molecule of CO₂?

Why does iodine, I₂ (s), spontaneously sublime at room temperature?

What is the number of moles of H₂O produced if you combust 0.5 mole of CH₄ according to the following balanced equation? CH₄ + 2 O₂ → CO₂ + 2 H₂O