Deck 8: Chemical Reactivity: Chemicals in Action

Question 1

According to the second law of thermodynamics,

A) the quality of energy is conserved, but he quantity of energy is not conserved
B) every naturally occurring process produces some entropy
C) perpetual motion is possible
D) efficiencies of energy transformations are expected to be 100%

Answer 1

every naturally occurring process produces some entropy

Question 2

If 2 pounds of hydrogen react with chlorine to form 73 pounds of hydrogen chloride, what weight of chlorine must react with the 2 pounds of hydrogen?
H₂(g) + Cl₂(g) $\rightarrow$ 2 HCl(g)

A) 71 pounds Cl₂(g)
B) 35.5 pounds Cl₂(g)
C) 2 pounds Cl₂(g)
D) weight of chlorine used depends on the reaction conditions

Answer 2

71 pounds Cl₂(g)

Question 3

For the equation, H₂(g) + Cl₂(g) $\rightarrow$ 2 HCl(g), which statement is false?

A) 1 mol of Cl₂(g) is a reactant
B) 2 molecules of HCl are formed
C) 4 grams of H₂(g) reacts with 1 mol of Cl₂(g)
D) the sum of the coefficients of the reactants is 2

Answer 3

4 grams of H₂(g) reacts with 1 mol of Cl₂(g)

Question 4

Which will increase the rate of a reaction?

A) increasing temperature
B) increasing temperature and concentration
C) increasing temperature and surface area
D) all of these

Question 5

What factors determine the rate of a reaction?

A) nature of reactants
B) concentration of reactants
C) activation energy
D) all of these

Question 6

Which will have the largest molar mass?

A) 1 mol of Ar, argon
B) 1 mol of CO, carbon monoxide
C) 1 mol of N₂, nitrogen
D) 1 mol of Sn, tin

Question 7

A chemical reaction that releases heat during the reaction is

A) exothermic
B) endothermic
C) a source of quick heat
D) impossible to reverse

Question 8

In all chemical changes,

A) reactants disappear completely
B) all of the reactants must cease to exist
C) the weight of products and reactants must balance
D) products must be in the same physical state as the reactants

Question 9

Refer to Exhibit 8-1.The atomic weights for Zn, H and Cl are 65.4, 1.0 and 35.5, respectively.What is the relative weight for two moles of hydrochloric acid?

A) 36.5
B) 71.0
C) 35.5
D) 73.0

Question 10

If you add more CO₂(g) to an equilibrium mixture of CaCO₃(s), CaO(s) and CO₂(g) in a hot closed vessel, which way would you expect the equilibrium to shift ? CaCO₃(s) $\harr$ CaO(s) + CO₂(g)

A) to form more reactant
B) to form more product
C) no change
D) indeterminable based in information given

Question 11

Refer to Exhibit 8-1.How many moles of hydrochloric acid react with one mole of zinc?

A) 1
B) 2
C) between 1 and 2 depending on how much hydrogen gas is formed
D) the same number as the number of moles of hydrogen produced

Question 12

For the equation, 2 NaN₃(s) $\rightarrow$ 2 Na(s) + 3 N₂(g), which statement is false?

A) the equation is balanced
B) the products are sodium and nitrogen
C) the sum of all coefficients is 7
D) the products are all in the same state of matter

Question 13

A catalyst speeds up a reaction rate because it

A) raises the reaction temperature
B) provides an alternate lower energy pathway
C) increases the energy of reactants
D) removes products from the reaction mixture

Question 14

What numbers are needed to balance the following equation? ____CO₂ + ____H₂O $\rightarrow$ ____C₆H₁₂O₆ + ____O₂

A) 1, 1, 1, 1
B) 6, 6, 6, 6
C) 6, 6, 1, 6
D) 6, 1, 1, 6

Question 15

What is the molar mass of H₂SO₄?

A) 50
B) 49
C) 98
D) 7

Question 16

Refer to Exhibit 8-1.What weight of ZnCl₂ will be produced from 1.00 mole of Zn?

A) 65.4 g
B) 98.9 g
C) 136.4 g
D) 71 g

Question 17

Which is not a statement of the First Law of Thermodynamics?

A) energy can be converted from one form to another
B) things are getting more screwed up every day
C) there's no such thing as a free lunch
D) you can't get something for nothing

Question 18

Preserving food by freezing controls reaction rates by

A) decreasing the number of collisions
B) increasing concentration
C) changing the number of effective reactant collisions
D) both a and c are correct

Question 19

Which is necessary for a chemical reaction to occur?

A) reactant molecules must collide
B) collisions must be of a certain energy
C) neither a nor b
D) both a and b

Question 20

According to the first law of thermodynamics,

A) energy is neither lost nor gained in an energy transformation
B) perpetual motion is possible
C) energy is not conserved
D) energy is being created as time passes

Question 21

If you remove some CO₂(g) from an equilibrium mixture of CaCO₃(s), CaO(s) and CO₂(g) in a hot closed vessel, which way would you expect the equilibrium to shift ? CaCO₃(s) $\harr$ CaO(s) + CO₂(g)

A) to form more reactant
B) to form more product
C) no change
D) indeterminable based in information given

Question 22

Favorable chemical reactions

A) are generally explosive
B) absorb energy from the surroundings
C) occur only in the gaseous phase
D) usually give off heat energy

Question 23

Which will have the smallest molar mass?

A) 1 mol of Ar, argon
B) 1 mol of CO₂, carbon monoxide
C) 1 mol of N₂, nitrogen
D) 1 mol of Sn, tin

Question 24

Which of the following samples has the most entropy?

A) 1 mol solid hydrogen
B) 1 mol liquid hydrogen
C) 1 mol hydrogen gas
D) all are the same because they are all hydrogen

Question 25

Chemical equilibrium exists for a chemical reaction when

A) equal amounts of chemicals exist on reactant and product sides
B) one or more of the reactants are used completely
C) all molecular activity stops
D) a state of balance exists between two opposite changes occurring at the same rate

Question 26

Le Chatelier's principle says

A) equilibrium mixtures are changed only when reactants are added
B) equilibrium mixtures will change to form more products when a reactant is added
C) the balance between reactants and products is not altered by changing the product concentration
D) equilibrium mixtures will not change when a stress is placed on the system

Question 27

How does changing concentration effect the rate of a chemical reaction?

A) increasing the concentration of a reactant will increase the reaction rate
B) the concentration has very little effect on reaction rates
C) the reaction rate increases only when all reactant concentrations are increased
D) increasing the concentration of products increases reaction rates

Question 28

Crumpling the pages of a newspaper to start a fire increases

A) surface contact
B) reactant available
C) equilibrium constant
D) temperature effect on reaction rate

Question 29

The three R's of waste prevention include

A) reuse products as much as possible
B) recycle materials as much as possible
C) reduce the amount of waste as much as possible
D) all of the above

Question 30

What is the sum of the coefficients when the following equation is balanced? Fe(s) + O₂(g) $\rightarrow$ Fe₂O₃(s)

A) 3
B) 6
C) 9
D) 10

Question 31

What is the number of atoms in a mole of nitrogen dioxide, NO₂?

A) 1.8 * 10²⁴
B) 1.8* 10²³
C) 2.0 *10²³
D) 3

Question 32

The use of a fire blanket in extinguishing a clothing fire is most closely related to what factor relative to chemical reaction rates?

A) temperature of reaction medium
B) catalysis
C) equilibrium ratio of reactants and products
D) concentration of reactants

Question 33

What is conserved when one balances a chemical equation?

A) molecules
B) atoms
C) products
D) reactants

Question 34

What is the molar mass of Al₂O₃?

A) 54
B) 86
C) 98
D) 102

Question 35

If you add more CaCO₃(s) to an equilibrium mixture of CaCO₃(s), CaO(s) and CO₂(g) in a hot closed vessel, which way would you expect the equilibrium to shift ? CaCO₃(s) $\harr$ CaO(s) + CO₂(g)

A) to form more reactant
B) to form more product
C) no change
D) indeterminable based in information given

Question 36

What is the weight of one mole of water molecules, H₂O? The atomic weight of hydrogen is 1 and the atomic weight of oxygen is 16.

A) 18 g H₂O
B) 18 H₂O
C) 6.02 * 10²³ g H₂O
D) 6.02 * 10²³ H₂O

Question 37

How many atoms are represented in the formula Ca₃(PO₄)₂?

A) 9
B) 11
C) 13
D) 1

Question 38

Which is a statement of the Second Law of Thermodynamics?

A) energy can be converted from one form to another
B) things are getting more screwed up every day
C) there's no such thing as a free lunch
D) you can't get something for nothing

Question 39

How will increasing the temperature effect the rate of a chemical reaction?

A) never increase
B) always decrease
C) usually increase
D) usually decrease

Question 40

What reaction rate factor is responsible for a dust explosion in a flour mill?

A) increased temperature
B) increased surface area
C) presence of catalysis
D) foreign chemicals

Question 41

How many grams are in 2.40 mol of carbon tetrachloride?

A) 0.0156
B) 370
C) 114
D) 0.0506

Question 42

How many atoms are in 7.50 g of sodium chloride?

A) 4.52 *10²⁴
B) 0.128
C) 7.73 * 10²²
D) 438

Question 43

How many atoms are in 5.43 mol of propane (C₃H₈)?

A) 9.02 * 10^-24
B) 240
C) 0.123
D) 3.27 * 10+²⁴

Question 44

How many moles are in 15.5 g of diphosphorous pentoxide?

A) 0.109
B) 0.330
C) 6.56 *10²³
D) 2.20 *10³