AnswersFoothill-B Period-Chemistry-2627BLab: Enthalpy

Lab: Enthalpy — Unit test Answers

15 verified answers
1
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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
–
–2,044.0 kJ/mol
–
–531.5 kJ/mol
5
531.5 kJ/mol
2
2,044.0 kJ/mol
2
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Which substance has Hf defined as 0 kJ/mol?

Question illustration
H
H2O (s)
N
Ne (l)
F
F2 (g)
C
CO2 (g)
3

Which statement defines specific heat capacity for a given sample?

t
the temperature of a given sample
t
the temperature that a given sample can withstand
t
the quantity of heat that is required to raise the sample’s temperature by 1°C (Kelvin)
t
the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure
4

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
5

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
2
22.5 kJ
3
30.0 kJ
3
31.5 kJ
6
61.5 kJ
6

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.
7

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
8

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

c
coffee cup calorimeter
b
bomb calorimeter
H
He could use both types of calorimeters.
H
He cannot use either.
9

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
–
–393.5 kJ
–
–196.8 kJ
1
196.8 kJ
3
393.5 kJ
10

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
0
0.0130 J/(gi°C)
0
0.0649 J/(gi°C)
0
0.193 J/(gi°C)
0
0.385 J/(gi°C)
11

The overall change in enthalpy of a reaction depends only on

t
the reactants and the products.
t
the path that is taken from the reactants to the products.
t
the reactants and the catalysts only.
t
the reactants, the products, and the catalysts.
12

Which energy change takes place when gasoline evaporates from a fuel gas can?

E
Energy is released.
E
Energy is absorbed.
E
Energy remains stationary.
E
Energy becomes transformed.
13

Which energy changes are associated with a liquid freezing?

E
Energy is released as potential energy increases.
E
Energy is absorbed as potential energy increases.
E
Energy is released as potential energy decreases.
E
Energy is absorbed as potential energy decreases.
14

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.
15

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

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