Question 1

Which of the following is a correctly balanced equation?

Accepted Answer

A) P4 + 6 H2 → 4 PH3 
B) 1 P4 + 6 H2 → 4 PH3 
C) 0 P4 + 6 H2 → 4 PH3 
D) 2 P4 + 12 H2 → 8 PH3 
E) P4 + 3 H2 → PH3 
A) P4 + 6 H2 → 4 PH3 
B) 1 P4 + 6 H2 → 4 PH3 
C) 0 P4 + 6 H2 → 4 PH3 
D) 2 P4 + 12 H2 → 8 PH3 
E) P4 + 3 H2 → PH3 A

Question 2

What is the formula mass of a molecule of C6H12O6?

Accepted Answer

A) 180 amu 
B) 24 amu 
C) 29 amu 
D) 168 amu 
E) none of the above 
A) 180 amu 
B) 24 amu 
C) 29 amu 
D) 168 amu 
E) none of the above A

Question 3

What is a chemical reaction?

Accepted Answer

A) when one or more new compounds are formed by rearranging atoms 
B) when a new element is formed by rearranging nucleons 
C) when two solids mix together to form a heterogeneous mixture 
D) when two liquids mix to form a homogeneous mixture 
E) when a liquid undergoes a phase change and produces a solid 
A) when one or more new compounds are formed by rearranging atoms 
B) when a new element is formed by rearranging nucleons 
C) when two solids mix together to form a heterogeneous mixture 
D) when two liquids mix to form a homogeneous mixture 
E) when a liquid undergoes a phase change and produces a solid A

Question 4

Why do the natural reactions involving ozone not lead to depletion of the ozone layer?

Accepted Answer

A) Ozone continually rises from the troposphere. 
B) Ozone is too diffuse. 
C) Ozone breaks into fragments that can reassemble into more ozone. 
D) UV radiation generates more ozone. 
E) c and d 
A) Ozone continually rises from the troposphere. 
B) Ozone is too diffuse. 
C) Ozone breaks into fragments that can reassemble into more ozone. 
D) UV radiation generates more ozone. 
E) c and d

Question 5

Balance these equations. ____ H2 (g)+ ____ N2 (g)→ ____ NH3 (g)

Accepted Answer

A) 2, 2, 3 
B) 2, 2, 5 
C) 3, 3, 2 
D) 3, 1, 2 
A) 2, 2, 3 
B) 2, 2, 5 
C) 3, 3, 2 
D) 3, 1, 2

Question 6

What is an endothermic 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

Question 7

How many grams of water can be formed from the reaction between 10 grams of oxygen and 1 gram of hydrogen?

Accepted Answer

A) 11 grams of water are formed since mass must be conserved. 
B) 10 grams of water are formed since you can't get a greater mass of water produced than oxygen reacting. 
C) 9 grams of water are formed because oxygen and hydrogen react in an 8:1 ratio. 
D) No water is formed because there is insufficient hydrogen to react with the oxygen. 
A) 11 grams of water are formed since mass must be conserved. 
B) 10 grams of water are formed since you can't get a greater mass of water produced than oxygen reacting. 
C) 9 grams of water are formed because oxygen and hydrogen react in an 8:1 ratio. 
D) No water is formed because there is insufficient hydrogen to react with the oxygen.

Question 8

According to the following balanced chemical equation, if you want to generate two moles of H2O how many grams of O2 do you need? 2 H2 + O2 → 2 H2O

Accepted Answer

A) 32 
B) 16 
C) 8 
D) 4 
E) 6.022 × 1023 
A) 32 
B) 16 
C) 8 
D) 4 
E) 6.022 × 1023

Question 9

How many grams of water, H2O, and propene, C3H6, can be formed from the reaction of 6.0 g of 2-propanol, C3H8O? C3H8O → C3H6 + H2O
2-Propanol Propene Water

Accepted Answer

A) 6.0 grams of propene, 0.0 grams of water 
B) 1.8 grams of propene, 4.2 grams of water 
C) 0.0 grams of propene, 6.0 grams of water 
D) 4.2 grams of propene, 1.8 grams of water 
A) 6.0 grams of propene, 0.0 grams of water 
B) 1.8 grams of propene, 4.2 grams of water 
C) 0.0 grams of propene, 6.0 grams of water 
D) 4.2 grams of propene, 1.8 grams of water

Question 10

If the relative mass of a hydrogen atom is 1/4 that of a helium atom, how many helium atoms would you need to equal the mass of 200 hydrogen atoms?

Accepted Answer

A) 50 
B) 200 
C) 800 
D) 4 
E) 100 
A) 50 
B) 200 
C) 800 
D) 4 
E) 100

Question 11

What is a chemical equation?

Accepted Answer

A) It is a shorthand notation for illustrating a chemical reaction. 
B) It is the sum of the masses of the products and reactants. 
C) It is the chemical combination of equal numbers of reactants and products. 
D) It is a picture of the atoms undergoing a chemical equalization. 
E) It is any type of reaction that takes place at the equator. 
A) It is a shorthand notation for illustrating a chemical reaction. 
B) It is the sum of the masses of the products and reactants. 
C) It is the chemical combination of equal numbers of reactants and products. 
D) It is a picture of the atoms undergoing a chemical equalization. 
E) It is any type of reaction that takes place at the equator.

Question 12

Wild plants readily grow "all by themselves" yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for a there to be this decrease in entropy for a process that occurs all by itself?

Accepted Answer

A) A decrease in entropy does not necessarily mean that a reaction if favored to proceed on its own. It happens in this instance but not in others. 
B) There is no decrease in entropy when wild plants grow. All growing plants tend to display an increase in entropy. 
C) Wild plants don't grow "all by themselves." When we consider the entire system, including the sun, we find an overall increase in entropy. 
D) Life on Earth "arises on its own." It does not depend on entropy processes. 
A) A decrease in entropy does not necessarily mean that a reaction if favored to proceed on its own. It happens in this instance but not in others. 
B) There is no decrease in entropy when wild plants grow. All growing plants tend to display an increase in entropy. 
C) Wild plants don't grow "all by themselves." When we consider the entire system, including the sun, we find an overall increase in entropy. 
D) Life on Earth "arises on its own." It does not depend on entropy processes.

Question 13

Carefully examine the following reaction sequence for the catalytic formation of ozone, O3, from molecular oxygen, O2. Which chemical compound is behaving as the catalyst? O2 + 2 NO → 2 N O2
2 N O2 → 2 NO + 2 O
2 O + 2 O2 → 2 O3

Accepted Answer

A) Nitrogen monoxide, NO 
B) Nitrogen dioxide, N O2 
C) Oxygen, O2 
D) Atomic oxygen, O 
A) Nitrogen monoxide, NO 
B) Nitrogen dioxide, N O2 
C) Oxygen, O2 
D) Atomic oxygen, O

Question 14

If the relative mass of a pingpong ball is 1/20 that of a golf ball, how many pingpong balls would you need to equal the mass of two golf balls?

Accepted Answer

A) 40 
B) 20 
C) 24 
D) 100 
E) 6.022 × 1023 
A) 40 
B) 20 
C) 24 
D) 100 
E) 6.022 × 1023

Question 15

Given that the above energy profiles have the same scale, which of the reactions would require the most energy?

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 16

Which equations are balanced? 
A.Mg (s)+ 2HCl (aq)→ MgCl2 (aq)+ H2 (g)
B.3Al (s)+ 3 Br2 (l)→ Al2Br3 (s)
C.2HgO (s)→ 2 Hg (l)+ O2 (g)

Accepted Answer

A) Only equation "c" is balanced. 
B) Equations "a" and "c" are balanced. 
C) Equations "b" and "c" are balanced. 
D) All of them are balanced. 
A) Only equation "c" is balanced. 
B) Equations "a" and "c" are balanced. 
C) Equations "b" and "c" are balanced. 
D) All of them are balanced.

Question 17

How is ozone produced in the upper atmosphere?

Accepted Answer

A) It forms by reaction of oxygen molecules with UV light. 
B) It forms by nuclear decomposition of oxygen. 
C) It diffuses from the lower atmosphere. 
D) It forms by the reaction of nitric dioxide and oxygen. 
E) all of the above 
A) It forms by reaction of oxygen molecules with UV light. 
B) It forms by nuclear decomposition of oxygen. 
C) It diffuses from the lower atmosphere. 
D) It forms by the reaction of nitric dioxide and oxygen. 
E) all of the above

Question 18

How many moles of water, H2O, are produced from the reaction of 16 grams methane, CH4, with an unlimited supply of oxygen, O2. How many grams of H2O is this? CH4 + 2 O2 → CO2 + 2 H2O

Accepted Answer

A) 0.889 mole, which is 16 grams 
B) 2.0 moles of water, which is 32 grams 
C) 2.0 moles of water, which is 36 grams 
D) 1.0 mole of water, which is 18 grams 
A) 0.889 mole, which is 16 grams 
B) 2.0 moles of water, which is 32 grams 
C) 2.0 moles of water, which is 36 grams 
D) 1.0 mole of water, which is 18 grams

Question 19

For the following balanced equation, which has the highest coefficient? 4 H2 + 2 C → 2 CH4

Accepted Answer

A) H2 
B) C 
C) CH4 
D) H4 
E) none of the above 
A) H2 
B) C 
C) CH4 
D) H4 
E) none of the above

Question 20

If it takes energy to break bonds and you gain energy in the formation of bonds, how can some reactions be exothermic while others are endothermic?

Accepted Answer

A) It is the total amount of energy that matters. Sometimes some bonds are stronger than others and so you gain or lose energy when you form them. 
B) It is the total number of bonds that matters. Sometimes you create more bonds than you break and since all bonds have same amount of energy you gain or lose energy depending on the number of bonds. 
C) Some reactants have more energetic bonds than others and they will always release energy. 
D) Some products have more energy than others and they always require energy to be formed. 
E) none of the above 
A) It is the total amount of energy that matters. Sometimes some bonds are stronger than others and so you gain or lose energy when you form them. 
B) It is the total number of bonds that matters. Sometimes you create more bonds than you break and since all bonds have same amount of energy you gain or lose energy depending on the number of bonds. 
C) Some reactants have more energetic bonds than others and they will always release energy. 
D) Some products have more energy than others and they always require energy to be formed. 
E) none of the above

Exam 17: How Chemicals React

Which of the following is a correctly balanced equation?

What is the formula mass of a molecule of C6H12O6?

What is a chemical reaction?

Why do the natural reactions involving ozone not lead to depletion of the ozone layer?

Balance these equations. ____ H2 (g)+ ____ N2 (g)→ ____ NH3 (g)

What is an endothermic reaction?

How many grams of water can be formed from the reaction between 10 grams of oxygen and 1 gram of hydrogen?

According to the following balanced chemical equation, if you want to generate two moles of H2O how many grams of O2 do you need? 2 H2 + O2 → 2 H2O

How many grams of water, H2O, and propene, C3H6, can be formed from the reaction of 6.0 g of 2-propanol, C3H8O? C3H8O → C3H6 + H2O 2-Propanol Propene Water

If the relative mass of a hydrogen atom is 1/4 that of a helium atom, how many helium atoms would you need to equal the mass of 200 hydrogen atoms?

What is a chemical equation?

Wild plants readily grow "all by themselves" yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for a there to be this decrease in entropy for a process that occurs all by itself?

Carefully examine the following reaction sequence for the catalytic formation of ozone, O3, from molecular oxygen, O2. Which chemical compound is behaving as the catalyst? O2 + 2 NO → 2 N O2 2 N O2 → 2 NO + 2 O 2 O + 2 O2 → 2 O3

If the relative mass of a pingpong ball is 1/20 that of a golf ball, how many pingpong balls would you need to equal the mass of two golf balls?

Given that the above energy profiles have the same scale, which of the reactions would require the most energy?

Which equations are balanced? A.Mg (s)+ 2HCl (aq)→ MgCl2 (aq)+ H2 (g) B.3Al (s)+ 3 Br2 (l)→ Al2Br3 (s) C.2HgO (s)→ 2 Hg (l)+ O2 (g)

How is ozone produced in the upper atmosphere?

How many moles of water, H2O, are produced from the reaction of 16 grams methane, CH4, with an unlimited supply of oxygen, O2. How many grams of H2O is this? CH4 + 2 O2 → CO2 + 2 H2O

For the following balanced equation, which has the highest coefficient? 4 H2 + 2 C → 2 CH4

If it takes energy to break bonds and you gain energy in the formation of bonds, how can some reactions be exothermic while others are endothermic?

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

What is the formula mass of a molecule of C₆H₁₂O₆?

Balance these equations. H₂ (g)+ N₂ (g)→ NH₃ (g)

According to the following balanced chemical equation, if you want to generate two moles of H₂O how many grams of O₂ do you need? 2 H₂ + O₂ → 2 H₂O

How many grams of water, H₂O, and propene, C₃H₆, can be formed from the reaction of 6.0 g of 2-propanol, C₃H₈O? C₃H₈O → C₃H₆ + H₂O 2-Propanol Propene Water

Carefully examine the following reaction sequence for the catalytic formation of ozone, O₃, from molecular oxygen, O₂. Which chemical compound is behaving as the catalyst? O₂ + 2 NO → 2 N O₂ 2 N O₂ → 2 NO + 2 O 2 O + 2 O₂ → 2 O₃

Which equations are balanced? A.Mg (s)+ 2HCl (aq)→ MgCl₂ (aq)+ H₂(g) B.3Al (s)+ 3 Br₂ (l)→ Al₂Br₃ (s) C.2HgO (s)→ 2 Hg (l)+ O₂ (g)

How many moles of water, H₂O, are produced from the reaction of 16 grams methane, CH₄, with an unlimited supply of oxygen, O₂. How many grams of H₂O is this? CH₄ + 2 O₂ → CO₂ + 2 H₂O

For the following balanced equation, which has the highest coefficient? 4 H₂ + 2 C → 2 CH₄