Question 1

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

Accepted Answer

A) 16 
B) 4 
C) 1/4 
D) 25 
E) 6.022 × 1023 
A) 16 
B) 4 
C) 1/4 
D) 25 
E) 6.022 × 1023

Question 2

Which equation best describes the reaction represented in the illustration above?

Accepted Answer

A) 2   + 2   +   → 2   + 2   
B) 2   + 2   +   → 2     + 2 DBA 
C) 2   + 2   +   → 2   + 2   
D) 2   + 2   +   → 2   + 2   
A) 2   + 2   +   → 2   + 2   
B) 2   + 2   +   → 2     + 2 DBA 
C) 2   + 2   +   → 2   + 2   
D) 2   + 2   +   → 2   + 2

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

Question 4

The yeast in bread dough feeds on sugar to produce carbon dioxide. Why does the dough rise faster in a warmer area?

Accepted Answer

A) There is a greater number of effective collisions among reacting molecules. 
B) Atmospheric pressure decreases with increasing temperature. 
C) The yeast tends to "wake up" with warmer temperatures, which is why baker's yeast is best stored in the refrigerator. 
D) The rate of evaporation increases with increasing temperature. 
A) There is a greater number of effective collisions among reacting molecules. 
B) Atmospheric pressure decreases with increasing temperature. 
C) The yeast tends to "wake up" with warmer temperatures, which is why baker's yeast is best stored in the refrigerator. 
D) The rate of evaporation increases with increasing temperature.

Question 5

A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?

Accepted Answer

A) The atoms (mass)of gasoline are converted into energy by the engine according to E=m   . 
B) The Law of Conservation of Mass does not apply to reactions involving combustion or explosion of matter. 
C) The atoms (mass)of gasoline are converted into exhaust fumes. 
D) The oil companies make gasoline in a way that it gets used up so that we are always required to replenish it. 
A) The atoms (mass)of gasoline are converted into energy by the engine according to E=m   . 
B) The Law of Conservation of Mass does not apply to reactions involving combustion or explosion of matter. 
C) The atoms (mass)of gasoline are converted into exhaust fumes. 
D) The oil companies make gasoline in a way that it gets used up so that we are always required to replenish it.

Question 6

What is the formula mass of sulfur dioxide, S   ?

Accepted Answer

A) about 16 amu 
B) about 32 amu 
C) about 60 amu 
D) about 64 amu 
A) about 16 amu 
B) about 32 amu 
C) about 60 amu 
D) about 64 amu

Question 7

In the laboratory, endothermic reactions are usually performed at elevated temperatures, while exothermic reactions are usually performed at lower temperatures. Why?

Accepted Answer

A) Endothermic reactions require the input of energy, which can include the input of thermal energy. Elevated temperatures help minimize unfavorable decrease in entropy due to the heat absorbed by the reaction. 
B) For exothermic reactions, the lower temperatures slow the reactive molecules down, which gives the chemist greater control. Also, the heat generated by the reaction is more efficiently dispersed under the colder conditions. 
C) Performing endothermic reactions at elevated temperature gives the molecules greater kinetic energy. Also, some exothermic reactions would explode if not run at cold temperatures. 
D) All of the above are true. 
A) Endothermic reactions require the input of energy, which can include the input of thermal energy. Elevated temperatures help minimize unfavorable decrease in entropy due to the heat absorbed by the reaction. 
B) For exothermic reactions, the lower temperatures slow the reactive molecules down, which gives the chemist greater control. Also, the heat generated by the reaction is more efficiently dispersed under the colder conditions. 
C) Performing endothermic reactions at elevated temperature gives the molecules greater kinetic energy. Also, some exothermic reactions would explode if not run at cold temperatures. 
D) All of the above are true.

Question 8

Which of the following statements accurately describes the action of ozone?

Accepted Answer

A) It absorbs UV radiation and undergoes fragmentation. 
B) It reflects UV radiation back into space. 
C) It reflects heat back into space. 
D) It emits UV radiation when excited by sunlight. 
E) none of the above 
A) It absorbs UV radiation and undergoes fragmentation. 
B) It reflects UV radiation back into space. 
C) It reflects heat back into space. 
D) It emits UV radiation when excited by sunlight. 
E) none of the above

Question 9

How many grams of water, H2O, can be produced from the reaction of 25.0 grams of hydrogen, H2, and 225 grams of oxygen, O2?

Accepted Answer

A) 250 grams 
B) 225 grams 
C) 200 grams 
D) 25 grams 
A) 250 grams 
B) 225 grams 
C) 200 grams 
D) 25 grams

Question 10

Entropy is a measure of ________.

Accepted Answer

A) disorder 
B) the spreading of energy 
C) solar energy 
D) thermodynamics 
A) disorder 
B) the spreading of energy 
C) solar energy 
D) thermodynamics

Question 11

The following diagrams depict the reaction between gaseous chlorine,   , and gaseous hydrogen,   , to form gaseous hydrogen chloride, HCl. What should be drawn in the empty box and how many grams of products are formed?

Accepted Answer

A) five   molecules in empty box; 37 grams of HCl + 36 grams of   
B) five   molecules in empty box; 71 grams of HCl + 1 gram of   
C) five HCl molecules in empty box; 50 grams of HCl + 22 grams of HCl 
D) five   molecules in empty box; 71 grams of HCl + 1 gram of   
A) five   molecules in empty box; 37 grams of HCl + 36 grams of   
B) five   molecules in empty box; 71 grams of HCl + 1 gram of   
C) five HCl molecules in empty box; 50 grams of HCl + 22 grams of HCl 
D) five   molecules in empty box; 71 grams of HCl + 1 gram of

Question 12

Some reactions are more sluggish than others. To speed up these reactions and save energy a(n)________ is sometimes added.

Accepted Answer

A) catalyst 
B) activator 
C) heat source 
D) exotherm 
E) reaction profile 
A) catalyst 
B) activator 
C) heat source 
D) exotherm 
E) reaction profile

Question 13

If it takes three carbon atoms to equal the mass of one chlorine atom, what mass 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 14

How many grams of gallium are there in a 145 gram sample of gallium arenside, GaAs?

Accepted Answer

A) 74.9 g 
B) 69.7 g 
C) 145 g 
D) 6.02 × 1023 g 
A) 74.9 g 
B) 69.7 g 
C) 145 g 
D) 6.02 × 1023 g

Question 15

What is the activation energy?

Accepted Answer

A) the minimum amount of energy to break the bonds in reactants 
B) the amount of energy required to activate a phase change 
C) the energy difference between the reactants and the products 
D) the amount of energy required to separate reactants from the products 
E) the hill 
A) the minimum amount of energy to break the bonds in reactants 
B) the amount of energy required to activate a phase change 
C) the energy difference between the reactants and the products 
D) the amount of energy required to separate reactants from the products 
E) the hill

Question 16

What coefficients balance the following equation? ____   (s)+ ____   (g)→ ____ P   (g)

Accepted Answer

A) 4, 2, 3 
B) 1, 6, 4 
C) 1, 4, 4 
D) 2, 10, 8 
A) 4, 2, 3 
B) 1, 6, 4 
C) 1, 4, 4 
D) 2, 10, 8

Question 17

Is the synthesis of ozone,   , from oxygen,   , an example of an exothermic or endothermic reaction?

Accepted Answer

A) exothermic because ultraviolet light is emitted during its formation 
B) endothermic because ultraviolet light is emitted during its formation 
C) exothermic because ultraviolet light is absorbed during its formation 
D) endothermic because ultraviolet light is absorbed during its formation 
A) exothermic because ultraviolet light is emitted during its formation 
B) endothermic because ultraviolet light is emitted during its formation 
C) exothermic because ultraviolet light is absorbed during its formation 
D) endothermic because ultraviolet light is absorbed during its formation

Question 18

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 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

If it takes 20 beryllium atoms to equal the mass of two krypton atoms, what is the relative mass of beryllium compared to krypton?

Accepted Answer

A) 1/10 
B) 1/20 
C) 40 times 
D) 100 times 
E) 10 times 
A) 1/10 
B) 1/20 
C) 40 times 
D) 100 times 
E) 10 times

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

Which equation best describes the reaction represented in the illustration above?

What is a chemical reaction?

The yeast in bread dough feeds on sugar to produce carbon dioxide. Why does the dough rise faster in a warmer area?

A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?

What is the formula mass of sulfur dioxide, S ?

In the laboratory, endothermic reactions are usually performed at elevated temperatures, while exothermic reactions are usually performed at lower temperatures. Why?

Which of the following statements accurately describes the action of ozone?

How many grams of water, H₂O, can be produced from the reaction of 25.0 grams of hydrogen, H₂, and 225 grams of oxygen, O₂?

Entropy is a measure of ________.

The following diagrams depict the reaction between gaseous chlorine, , and gaseous hydrogen, , to form gaseous hydrogen chloride, HCl. What should be drawn in the empty box and how many grams of products are formed?

Some reactions are more sluggish than others. To speed up these reactions and save energy a(n)________ is sometimes added.

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

How many grams of gallium are there in a 145 gram sample of gallium arenside, GaAs?

What is the activation energy?

What coefficients balance the following equation? (s)+ (g)→ P (g)

Is the synthesis of ozone, , from oxygen, , an example of an exothermic or endothermic reaction?

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?

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

If it takes 20 beryllium atoms to equal the mass of two krypton atoms, what is the relative mass of beryllium compared to krypton?

About Science

Particles of Matter

Elements of Chemistry

Subatomic Particles

The Atomic Nucleus

How Atoms Bond

How Molecules Mix

How Water Behaves

Acids and Bases in Our Environment

Oxidations and Reductions Charge the World

Organic Compounds

Nutrients of Life

Medicinal Chemistry

Optimizing Food Production

Protection Water and Air Resources

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Exam 9: How Chemicals React

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

Which equation best describes the reaction represented in the illustration above?

What is a chemical reaction?

The yeast in bread dough feeds on sugar to produce carbon dioxide. Why does the dough rise faster in a warmer area?

A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?

What is the formula mass of sulfur dioxide, S ?

In the laboratory, endothermic reactions are usually performed at elevated temperatures, while exothermic reactions are usually performed at lower temperatures. Why?

Which of the following statements accurately describes the action of ozone?

How many grams of water, H2O, can be produced from the reaction of 25.0 grams of hydrogen, H2, and 225 grams of oxygen, O2?

Entropy is a measure of ________.

The following diagrams depict the reaction between gaseous chlorine, , and gaseous hydrogen, , to form gaseous hydrogen chloride, HCl. What should be drawn in the empty box and how many grams of products are formed?

Some reactions are more sluggish than others. To speed up these reactions and save energy a(n)________ is sometimes added.

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

How many grams of gallium are there in a 145 gram sample of gallium arenside, GaAs?

What is the activation energy?

What coefficients balance the following equation? ____ (s)+ ____ (g)→ ____ P (g)

Is the synthesis of ozone, , from oxygen, , an example of an exothermic or endothermic reaction?

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?

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

If it takes 20 beryllium atoms to equal the mass of two krypton atoms, what is the relative mass of beryllium compared to krypton?

About Science

Particles of Matter

Elements of Chemistry

Subatomic Particles

The Atomic Nucleus

How Atoms Bond

How Molecules Mix

How Water Behaves

Acids and Bases in Our Environment

Oxidations and Reductions Charge the World

Organic Compounds

Nutrients of Life

Medicinal Chemistry

Optimizing Food Production

Protection Water and Air Resources

Capturing Energy

Filters

How many grams of water, H₂O, can be produced from the reaction of 25.0 grams of hydrogen, H₂, and 225 grams of oxygen, O₂?

What coefficients balance the following equation? (s)+ (g)→ P (g)

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