AnswersFoothill-B Period-Chemistry-2627BCumulative Exam

Cumulative Exam — Cumulative exam Answers

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According to Le Chatelier’s principle, what happens when the concentration of a product is reduced in a chemical reaction that was in equilibrium?

T
The equilibrium shifts to the right to favor the formation of products.
T
The equilibrium shifts to the left to favor the formation of reactants.
T
The equilibrium shifts in the exothermic direction.
T
The equilibrium shifts in the endothermic direction.
2
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Look at the diagram of a fuel cell used to power a motorized vehicle.Which part of the fuel cell does A represent?

Question illustration
a
anode
c
cathode
e
electrolyte
m
motor
3

Consider the chemical equation in equilibrium. A(g) + 2B(g) C(g) + D(g) + heat What will happen to the equilibrium of this reaction if the temperature is increased?

Question illustration
I
It will shift to the left because heat is released.
I
It will shift to the left because heat is absorbed.
I
It will shift to the right because heat is released.
I
It will shift to the right because heat is absorbed.
4

According to the enthalpy diagram below, which of the following statements is true?

Question illustration
A
Arrows A and D represent the enthalpy of the intermediate chemical reactions.
A
Arrow C represents the enthalpy of the overall chemical reaction.
A
Arrow C indicates that the third intermediate reaction is exothermic.
A
Arrow B indicates that the second intermediate reaction is exothermic.
5

Which type of reaction does this diagram represent?

Question illustration
a
a chain reaction that is caused by nuclear fission
a
a chain reaction that is caused by nuclear fusion
a
a decrease in energy that is caused by nuclear fission
a
an increase in energy that is caused by nuclear fusion
6

Hydrogen fuel cells that operate at lower temperatures use more expensive platinum electrode catalysts. What helps to make up for the higher-cost electrodes?

T
They use a cheaper fuel.
T
They operate at a higher efficiency.
T
They use a reaction that is not redox.
T
They produce fewer emissions.
7

When ammonium chloride is dissolved in water, the beaker gets cold. Which type of reaction does this describe?

e
exothermic
e
endothermic
b
both exothermic and endothermic
n
neither exothermic nor endothermic
8

best

T
The temperature increases because the average kinetic energy decreases.
T
The temperature increases because the average kinetic energy increases.
T
The temperature decreases because the average kinetic energy decreases.
T
The temperature decreases because the average kinetic energy increases.
9

The combustion of glucose, C6 H12 O6 (s), produces carbon dioxide, CO2 (g), and water, H2 O(g), according to the equation below.The enthalpy of the reaction is –2,840 kJ. What is the heat of combustion, per mole, of glucose?

Question illustration
–
–2,840 kJ/mol
–
–473.3 kJ/mol
4
473.3 kJ/mol
2
2,840 kJ/mol
10

Which defines the average kinetic energy of a system’s particles?

d
density
p
pressure
t
temperature
v
volume
11

The molar heat of fusion for water is 6.01 kJ/mol. How much energy is released when 36.8 g of water freezes at its freezing point?Use .

Question illustration
6
6.12 kJ
1
12.3 kJ
1
108 kJ
2
221 kJ
12

According to Le Chatelier’s principle, a change in pressure affects the chemical equilibrium of the reaction system under what condition?

T
The reactants and the products are in the solid phase.
T
The reactants and the products are in the liquid phase.
S
Some of the reactants or the products are in the gaseous phase.
S
Some of the reactants or the products are solid, and some are liquid.
13

A book is falling from the top shelf of a bookcase. Which statement correctly describes the change in the energy of the book?

T
The potential energy and kinetic energy remain the same.
T
The potential energy decreases as kinetic energy increases.
T
The kinetic energy decreases as potential energy increases.
T
The kinetic energy remains at zero, but potential energy increases.
14

The molar heat of fusion of gold is 12.550 kJ mol–1. At its melting point, how much mass of melted gold must solidify to release 235.0 kJ of energy?Use .

Question illustration
1
18.73 g
2
222.5 g
2
2,949.3 g
3
3,688.3 g
15

How does an increase in reactant concentration affect the rate of reaction?

I
It leads to more frequent collisions, which increase reaction rate.
I
It leads to less frequent collisions, which increase reaction rate.
I
It leads to more frequent collisions, which decrease reaction rate.
I
It leads to less frequent collisions, which decrease reaction rate.
16

Which substance loses electrons in a chemical reaction?

t
the one that is oxidized, which is the oxidizing agent
t
the one that is reduced, which is the reducing agent
t
the one that is oxidized, which is the reducing agent
t
the one that is reduced, which is the oxidizing agent
17

After a radioactive atom decays, it is the same element that it was before with no measurable change in mass. Which kind of decay has occurred, and how do you know?

a
alpha decay because alpha particles have no mass
b
beta decay because this kind of decay cannot change one element into another
a
alpha decay because it creates a new isotope of the same element
g
gamma decay because photons have no mass
18

best

A
A nucleus spontaneously splits and absorbs energy.
T
Two nuclei spontaneously combine and absorb energy.
A
A nucleus collides with a neutron and splits, releasing energy.
N
Nuclei combine to form a heavier nucleus, releasing energy.
19

Which statement describes the law of conservation of energy?

A
All systems will exchange matter and energy with their surroundings.
A
All systems can exchange energy, but not matter, with their surroundings.
E
Energy cannot be created nor destroyed, but it changes from one form to another.
E
Energy is destroyed in most chemical reactions when new products are formed.
20

best

a
a colloid
a
a suspension
a
a solution
a
an alloy

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