AnswersSY2026-27 - 2003340 Chemistry 1 Sem 2 CRWriting and Balancing Chemical Equations

Writing and Balancing Chemical Equations — Unit test Answers

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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.
2
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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
A
–2,044.0 kJ/mol
B
–531.5 kJ/mol
C
531.5 kJ/mol
D
2,044.0 kJ/mol
3

Which substance has Hf defined as 0 kJ/mol?

Question illustration
A
H2O (s)
B
Ne (l)
C
F2 (g)
D
CO2 (g)
4

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.
5

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
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 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.
8

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
9

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.
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

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
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 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
14

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.
15

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

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