AnswersTX-Chemistry BUnit Test

Unit Test — Unit test Answers

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Which type of reaction is always spontaneous?

A
an exothermic reaction that has an increase in disorder
B
an exothermic reaction that has a decrease in disorder
C
an endothermic reaction that has an increase in disorder
D
an endothermic reaction that has a decrease in disorder
2
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A copper rod that has a mass of 200.0 g has an initial temperature of 20.0°C and is heated to 40.0°C. If 1,540 J of heat are needed to heat the rod, what is the specific heat of copper?Use .

Question illustration
A
0.0130 J/(gi°C)
B
0.0649 J/(gi°C)
C
0.193 J/(gi°C)
D
0.385 J/(gi°C)
3

What is Gsystem for the system that is described by the following data?Hsystem = –345 kJ, T = 293 K, Ssystem = 465 J/KGsystem = Hsystem – TSsystem

Question illustration
A
–481 kJ
B
–209 kJ
C
413 kJ
D
135,900 kJ
4

Reactant P contains 50 J of energy, and reactant Q contains 35.3 J of energy. The reactants combine to form product PQ, which contains 104 J of energy. What is the energy transformation?

A
Energy is absorbed because the product has more energy than the reactants have.
B
Energy is absorbed because the product has less energy than the reactants have.
C
Energy is lost because the product has more energy than the reactants have.
D
Energy is lost because the product has less energy than the reactants have.
5

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
A
–2,840 kJ/mol
B
–473.3 kJ/mol
C
473.3 kJ/mol
D
2,840 kJ/mol
6

Which statement describes the law of conservation of energy?

A
All systems will exchange matter and energy with their surroundings.
B
All systems can exchange energy, but not matter, with their surroundings.
C
Energy cannot be created nor destroyed, but it changes from one form to another.
D
Energy is destroyed in most chemical reactions when new products are formed.
7

Propane (C3 H8 (g), Hf = –103.8 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Hf = –393.5 kJ/mol ) and water (H2 O, Hf = –241.82 kJ/mol) according to the equation below.What is the enthalpy of combustion (per mole) of C3 H8 (g)? Use .

Question illustration
A
–2,044.0 kJ/mol
B
–531.5 kJ/mol
C
531.5 kJ/mol
D
2,044.0 kJ/mol
8

Carbon reacts with oxygen to produce carbon dioxide (CO2 (g), Hf = –393.5 kJ/mol) according to the equation below.What is the enthalpy change of the reaction? Use .

Question illustration
A
–393.5 kJ
B
–196.8 kJ
C
196.8 kJ
D
393.5 kJ
9

A sample of octane (C8H18) that has a mass of 0.750 g is burned in a bomb calorimeter. As a result, the temperature of the calorimeter increases from 21.0°C to 41.0°C. The specific heat of the calorimeter is 1.50 J/(g • °C), and its mass is 1.00 kg. How much heat is released during the combustion of this sample?Use .

Question illustration
A
22.5 kJ
B
30.0 kJ
C
31.5 kJ
D
61.5 kJ
10

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

A
density
B
pressure
C
temperature
D
volume
11

Which substance has Hf defined as 0 kJ/mol?

Question illustration
A
H2O (s)
B
Ne (l)
C
F2 (g)
D
CO2 (g)
14

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

A
The potential energy and kinetic energy remain the same.
B
The potential energy decreases as kinetic energy increases.
C
The kinetic energy decreases as potential energy increases.
D
The kinetic energy remains at zero, but potential energy increases.
15

Which statement defines specific heat capacity for a given sample?

A
the temperature of a given sample
B
the temperature that a given sample can withstand
C
the quantity of heat that is required to raise the sample’s temperature by 1°C (Kelvin)
D
the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure
16

Which statement best explains the change that occurs when gas particles move more slowly?

A
The temperature increases because the average kinetic energy decreases.
B
The temperature increases because the average kinetic energy increases.
C
The temperature decreases because the average kinetic energy decreases.
D
The temperature decreases because the average kinetic energy increases.
17

Consider the following equation.Fe2O3(s) + 3H2(g) 2Fe(s) + 3H2O(g)H = 98.8 kJ, and S = 141.5 J/K. Is this reaction spontaneous or nonspontaneous at high and low temperatures?

Question illustration
A
spontaneous at high temperatures, nonspontaneous at low temperatures
B
nonspontaneous at high and low temperatures
C
spontaneous at low temperatures, nonspontaneous at high temperatures
D
spontaneous at high and low temperatures
18

An ice cube is dropped into a glass of milk at 20°C. Which statement explains the transfer of kinetic energy (KE)?

A
Because milk has higher KE than ice, KE is transferred from the milk to the molecules of ice.
B
Because milk has higher KE than ice, KE is transferred from the molecules of ice to the milk.
C
Because ice has higher KE than milk, KE is transferred from the milk to the molecules of ice.
D
Because ice has higher KE than milk, KE is transferred from the molecules of ice to the milk.
19

Digby wants to determine how many calories are in his bag of chips. Which calorimeter should he use?

A
coffee cup calorimeter
B
bomb calorimeter
C
He could use both types of calorimeters.
D
He cannot use either.
20

What is the definition of entropy?

A
a system that can exchange both matter and energy with its surroundings
B
a measure of the overall disorder of a system
C
a quantity that measures the overall spontaneity of a reaction
D
a process that will proceed without continuous external influence
21

Which statement describes mechanical energy?

A
the energy that is stored in chemical bonds
B
the energy that is associated with temperature
C
the sum of the kinetic energy and the potential energy of an object
D
the type of energy that is associated with electromagnetic radiation

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