AnswersChemistry Credit Recovery BEnthalpy of Reaction

Enthalpy of Reaction — Unit test Answers

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1
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Which energy changes are associated with a liquid freezing?

A
Energy is released as potential energy increases.
B
Energy is absorbed as potential energy increases.
C
Energy is released as potential energy decreases.
D
Energy is absorbed as potential energy decreases.
2
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What must occur for the enthalpy of solution to be negative?

A
The process of separating the solvent particles from one another must release energy.
B
The process of separating the solute particles from one another must release energy.
C
More energy is absorbed as the solute and solvent mix than is released when the solute particles and the solvent particles separate.
D
More energy is released as the solute and solvent mix than is absorbed when the solute particles and the solvent particles separate.
3

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.
4

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
A
18.73 g
B
222.5 g
C
2,949.3 g
D
3,688.3 g
5

What is the Hsol for KF + ? The lattice energy is –784 kJ/mol, the enthalpy of hydration for is –336 kJ/mol, and the enthalpy of hydration for is –431 kJ/mol. Use Hsol = –Hlat + Hhydr.

Question illustration
A
–879 kJ/mol
B
–17 kJ/mol
C
17 kJ/mol
D
1,551 kJ/mol
6

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.
7

Which statement defines the enthalpy of hydration?

A
the change in enthalpy when 1 mol of a gaseous ion becomes fully hydrated
B
the change in enthalpy when gas ions condense to form 1 mol of an ionic solid
C
the change in enthalpy as heat is lost or gained in a reaction
D
the change in enthalpy as temperature rises in a liquid
8

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)
9

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.
10

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

A
density
B
pressure
C
temperature
D
volume
11

Consider the diagram below.Which answer accurately describes the diagram?

Question illustration
A
The temperature decreases, and the process is exothermic.
B
The temperature decreases, and the process is endothermic.
C
The temperature increases, and the process is exothermic.
D
The temperature increases, and the process is endothermic.
12

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.
13

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
14

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
15

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

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