Deck 12: Chemical Reactions

Question 1

The speed of a chemical reaction is not affected by

A)the surface area of the reactants.
B)catalysts.
C)the concentration of reactants.
D)the type of bond in reaction products.

Answer 1

the type of bond in reaction products.

Question 2

The decomposition of an unstable compound usually

A)occurs only at low temperatures.
B)requires a catalyst to occur.
C)is endothermic.
D)is exothermic.

Answer 2

is exothermic.

Question 3

One mole of which of the following compounds contains the largest number of fluorine atoms?

A)HF
B)SF₂
C)BF₃
D)XeF₆

Answer 3

XeF₆

Question 4

If a certain reaction is endothermic, the reverse reaction

A)cannot occur.
B)may occur spontaneously.
C)cannot occur spontaneously.
D)absorbs energy.

Question 5

Approximately 4/5 of dry air consists of

A)oxygen.
B)nitrogen.
C)carbon dioxide.
D)argon.

Question 6

The mass of 1 mole of oxygen, O₂, is 32 g.The atomic mass of oxygen is

A)16 u.
B)16 g.
C)32 u.
D)32 g.

Question 7

An example of slow oxidation is

A)a lighted candle.
B)the rusting of iron.
C)the lighting of a match.
D)a log burning in a fireplace.

Question 8

The chief reason why reaction rates increase with temperature is that a rise in temperature increases the number of

A)ions.
B)polar molecules.
C)fast-moving molecules.
D)activated molecules.

Question 9

According to Aristotle, every flammable material consisted of

A)earth and fire.
B)phlogiston.
C)oxygen and earth.
D)air and heat.

Question 10

An oxide decomposed by heating will give

A)oxygen and another element.
B)CO₂ and water.
C)oxygen ions and metal ions.
D)a metal and water.

Question 11

Chemical reactions that give off energy are called

A)endothermic.
B)exothermic.
C)activated.
D)oxidation-reduction.

Question 12

A mole of any compound contains Avogadro's number of

A)atoms.
B)ions.
C)molecules.
D)formula units.

Question 13

For a reaction that takes place near room temperature, an increase of 10 ^$\circ$ C

A)has almost no effect on the reaction speed.
B)increases the reaction speed by about 10%.
C)increases the reaction speed by about 50%.
D)approximately doubles the reaction speed.

Question 14

The time needed for a strong acid to neutralize a strong base in solution

A)decreases with temperature.
B)increases with temperature.
C)is virtually independent of temperature.
D)Any of these choices could be correct, depending on the particular acid and base.

Question 15

When 1 g of a metal is oxidized, the resulting oxide has a mass that is

A)less than 1 g.
B)equal to 1 g.
C)more than 1 g.
D)Any of these choices could be correct, depending on the metal.

Question 16

Which of the following compounds is not classed as an oxide?

A)CO₂
B)SiO₂
C)BaSO₄
D)H₂O

Question 17

An example of an exothermic process is the

A)dissociation of a salt in water solution.
B)neutralization of an acid by a base.
C)electrolysis of water.
D)melting of ice.

Question 18

The energy liberated in a chemical reaction comes from the

A)kinetic energy of atomic electrons.
B)potential energy of atomic electrons.
C)activation energy of atomic electrons.
D)equilibrium energy of atomic electrons.

Question 19

The scientist whose experiments showed that tin, upon heating, combined with a gas from the air was

A)Priestley.
B)Stahl.
C)Lavoisier.
D)Becher.

Question 20

Which of the following statements about ozone is incorrect?

A)The formula of ozone is O₃.
B)Ozone molecules are more stable than those of ordinary oxygen.
C)At low altitudes ozone contributes to smog.
D)At high altitudes ozone absorbs solar ultraviolet radiation.

Question 21

The number of moles of atomic oxygen in 1 mole of Ca₃(PO₄)₂ is

A)1.
B)2.
C)4.
D)8.

Question 22

Oxidation-reduction reactions involve the transfer between the reacting substances of

A)electrons.
B)H⁺ ions.
C)O_2- ions.
D)O₂ molecules.

Question 23

The number of calcium atoms in 1 mole of calcium is

A)40.
B)1.5 * 10²².
C)3 * 10²².
D)6 * 10²³.

Question 24

Most chemical reactions

A)absorb energy.
B)occur at rates that are independent of temperature.
C)are reversible.
D)produce precipitates.

Question 25

The number of moles of Al needed to react with each mole of CuSO₄ in the reaction 2Al + 3CuSO₄ $\rarr$ 3 Cu + Al₂(SO₄)₃ is

A)1/3.
B)1/2.
C)2/3.
D)3/2.

Question 26

Ammonia gas dissolves in water and can react according to the equation NH₃ + H₂O NH₄⁺ OH^-.The amount of ammonium ion in solution will be increased by which one or more of the following?

A)Increase the pressure of NH₃ above the solution.
B)Pump off the gas above the solution.
C)Raise the temperature of the solution.
D)Add HCl to the solution.
E)Both A and D

Question 27

The number of calcium atoms in 1 g of calcium is

A)40.
B)1.5 * 10²².
C)3 * 10²².
D)6 * 10²³.

Question 28

Silicon has an atomic mass of 28 u and Avogadro's number is 6 *10²³ formula units/mole.The mass of 1 mole of silicon is

A)1 g.
B)28 g.
C)6 * 10²³ g.
D)1.68 * 10²⁵ g.

Question 29

Chemical reactions in solution do not depend to any great extent upon

A)pressure.
B)temperature.
C)concentration.
D)catalysts.

Question 30

A chemical equilibrium occurs when the

A)mass of the products equals the mass of the reactants.
B)number of molecules of the products equals the number of molecules of the reactants.
C)concentration of the products equals the concentration of the reactants.
D)speed of the forward reaction equals the speed of the reverse reaction.

Question 31

The mass of Avogadro's number of silicon atoms is

A)1 g.
B)28 g.
C)6 * 10²³ g.
D)1.68 * 10²⁵ g.

Question 32

An enzyme is a

A)gasoline additive that reduces pollution.
B)constituent of natural gas.
C)solvent used in electrolysis.
D)biological catalyst.

Question 33

The yield of the product C in the reversible reaction A + B C + energy can be increased by

A)decreasing the temperature.
B)increasing the temperature.
C)increasing the surface area of the reactants.
D)changing the catalyst.

Question 34

In the electrolysis of molten NaCl, the substance liberated at the positive electrode is

A)Cl^-.
B)Cl₂.
C)Na⁺.
D)Na.

Question 35

When a gas reaction involves an increase in the number of molecules present, the yield can be increased by

A)increasing the pressure.
B)decreasing the pressure.
C)increasing the temperature.
D)decreasing the temperature.

Question 36

Oxidation-reduction reactions are not involved in

A)electrolysis.
B)acid-base neutralization.
C)the operation of a storage battery.
D)the operation of a fuel cell.

Question 37

The atomic mass of N is 14 u and that of Ca is 40 u.The proportion of N by mass in the compound Ca₃N₂ is

A)19 percent.
B)35 percent.
C)40 percent.
D)81 percent.

Question 38

When a substance gains electrons in a chemical reaction, the substance is said to be

A)reduced.
B)oxidized.
C)dissociated.
D)activated.

Question 39

The number of moles of H₂O formed when 1 mole of O₂ reacts with C₅H₁₂ in the reaction C₅H₁₂ + 8O₂ $\rarr$ 5CO₂ + 6H₂O is

A)3/4.
B)4/3.
C)6.
D)8.

Question 40

The number of moles of O₂ needed to react with 10 moles of C₂H₂ in the reaction 2C₂ H₂ + 5O₂ $\rarr$ 4CO₂ + 2 H₂O is

A)5.
B)10.
C)25.
D)50.