AnswersCR Chemistry S1 Q3050OXUnit Test

Unit Test — Unit test Answers

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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
2
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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
3

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.
4

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
5

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)
6

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
7

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

A
exothermic
B
endothermic
C
both exothermic and endothermic
D
neither exothermic nor endothermic
8

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
9

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.
10

According to Hess’s law, if a series of intermediate reactions are combined, the enthalpy change of the overall reaction is

A
the difference between the enthalpies of the intermediate reactions.
B
the sum of the enthalpy changes of the intermediate reactions.
C
the product of the enthalpy changes of the intermediate reactions.
D
the fraction of the individual enthalpies of the intermediate reactions.
11

Which substance has Hf defined as 0 kJ/mol?

Question illustration
A
H2O (s)
B
Ne (l)
C
F2 (g)
D
CO2 (g)
12

The overall change in enthalpy of a reaction depends only on

A
the reactants and the products.
B
the path that is taken from the reactants to the products.
C
the reactants and the catalysts only.
D
the reactants, the products, and the catalysts.
13

Consider the following intermediate chemical equations.What is the enthalpy of the overall chemical reaction ?

Question illustration
A
-4,580 kJ
B
-1,300 kJ
C
1,300 kJ
D
4,580 kJ
14

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.
B
Arrow C represents the enthalpy of the overall chemical reaction.
C
Arrow C indicates that the third intermediate reaction is exothermic.
D
Arrow B indicates that the second intermediate reaction is exothermic.
15

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.

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