AnswersEO Chemistry 7320CUnit Test

Unit Test — Unit test Answers

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Which statement best describes the reaction pathway graph for an exothermic reaction but not an endothermic reaction?

A
It has a hill in the middle that is the highest point.
B
It has a valley in the middle that is its lowest point.
C
The reactants are higher in energy than the products.
D
The products are higher in energy than the reactants.
2
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A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A
It increased the number of molecular collisions.
B
It decreased the number of molecular collisions.
C
It decreased the space between the molecules and lowered the reaction rate.
D
It increased the space between the molecules and increased the reaction rate.
3

Which of these refers to the strength of an acid?

A
a measure of the quantity of acid dissolved in water designated by molarity
B
an intrinsic characteristic of a particular acid, not related to concentration
C
the amount of hydrogen ions present in the acid
D
the amount of hydroxide ions present in a solution
4

The table below lists some acids and bases.Strong acidsWeak acidsWeak basesStrong basesHBrCH3COOHNH3NaOHHNO3HCOOHNH4OHKOHH2SO4 Ca(OH)2Which reaction yields a salt that has a pH < 7?

A
mc013-1.jpg
Option A
B
mc013-2.jpg
Option B
C
mc013-3.jpg
Option C
D
mc013-4.jpg
Option D
5

Consider the reaction pathway below.Which is true about the potential energy of the reactants in this reaction pathway?

Question illustration
A
It is greater than the potential energy of the products.
B
It is less than the potential energy of the products.
C
It is equal to the potential energy of the products.
D
It is half of the potential energy of the products.
6

Soaps feel slippery on our hands because they dissolve the oil on our skin, decreasing friction.This is because soap contains

A
a neutral molecule.
B
a salt molecule.
C
an acid.
D
a base.
7

What type of substance reacts with limestone (CaCO3) and produces carbon dioxide gas?

A
a neutral substance
B
a base
C
an acid
D
both an acid and a base
8

Which energy graph represents the nonspontaneous transition of graphite into diamond?

A
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts low on the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down a short distance, and levels out.
Option A
B
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down sharply, and levels out below the initial starting point.
Option B
C
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a small amount, then curves down to level out below the initial starting point.
Option C
D
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a moderate amount, then curves down sharply to level out below the initial starting point.
Option D
9

A solution of ammonia has a pH of 11.8. What is the concentration of OH– ions in the solution?Useful formulas include , , , and .

Question illustration
A
1.58 10–12 M
Option A
B
6.31 10–3 M
Option B
C
2.20 M
D
158 M
10

Consider the reaction below.Which is the net ionic equation for the reaction?

Question illustration
A
Upper H superscript plus, plus upper C l superscript minus right arrow upper H upper C l.
Option A
B
Upper N a superscript plus, plus upper C l superscript minus right arrow upper N a upper C l.
Option B
C
Upper N a superscript plus, plus upper C subscript 2 upper H subscript 3 upper o subscript 2 superscript minus (a q) plus upper H superscript plus, right arrow upper N a upper C subscript 2 upper H subscript 3 upper O subscript 2.
Option C
D
Upper C subscript 2 upper h subscript 3 upper O subscript 2 superscript minus (a q) plus upper H superscript plus right arrow upper H upper C subscript 2 upper H subscript 3 upper O subscript 2.
Option D
11

A strong acid, HA, is added to water. Which statement about the solution is true?

A
It contains mostly hydroxide ions.
B
It contains almost no hydronium ions.
C
It contains little or no HA.
D
It contains a low amount of ions.
12

Which of these correctly defines the pOH of a solution?

A
the log of the hydronium ion concentration
B
the negative log of the hydronium ion concentration
C
the log of the hydroxide ion concentration
D
the negative log of the hydroxide ion concentration
13

Which statement best applies collision theory to preventing a dangerous reaction from occurring?

A
Store the reactants together at a low pressure.
B
Keep all sparks or flames away from the reactants.
C
Store the reactants together at a low temperature.
D
Keep the reactants in separate containers.
14

Consider the reaction pathway graph below. Which method would provide evidence to support the inference that this is an exothermic reaction?

Question illustration
A
add A and C
B
add E and D
C
subtract A from C
D
subtract E from D
15

Consider the reaction pathway graph below.Which letter represents the activated complex?

Question illustration
A
A
B
B
C
F
D
G
16

What happens as the activation energy increases?

A
The pressure of the system decreases.
B
The kinetic energy of colliding molecules changes.
C
The reactant surface area decreases.
D
The reaction begins to slow down.
17

What does it mean for a strong base to be in equilibrium?

A
The position of equilibrium lies far to the right, with products being favored.
B
The position of equilibrium lies far to the left, with products being favored.
C
There is a great deal of base and very few ions.
D
There is an equal amount of reactants and products.
18

An unknown substance turns blue litmus paper to red. Which additional test could be used to confirm the substance’s identity?

A
It should turn phenolphthalein from colorless to pink because it is a base.
B
It should turn phenolphthalein from pink to colorless because it is a base.
C
It should turn methyl orange to orange because it is an acid.
D
It should turn methyl orange to red because it is an acid.
19

Which pair of substances would most likely result in the production of a gas when reacting with an acid?

A
litmus and methyl orange
B
base and salt
C
metal and carbonate
D
carbon dioxide and water
20

Which of the following is the correctly balanced chemical equation for the reaction of Ca(OH)2 and HNO3?

A
Upper C a (upper O upper H) subscript 2 plus upper H upper N upper O subscript 3 right arrow upper C a superscript 2 plus, plus upper N upper O subscript 3 superscript minus.
Option A
B
Upper C a (upper O upper H) subscript 2 plus 2 upper H upper N upper O subscript 3 right arrow 2 upper H subscript 2 upper O plus 2 upper N upper O subscript 3 superscript minus
Option B
C
Upper C a (upper O upper H) subscript 2 plus upper H upper N upper O subscript 3 right arrow upper H subscript 2 upper O plus upper C a upper N upper O subscript 3.
Option C
D
Upper C a (upper O upper H) subscript 2 plus 2 upper H upper N upper O subscript 3 right arrow 2 upper H subscript 2 upper O plus UPper C a (upper N upper O subscript 3) subscript 2.
Option D

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