AnswersChemistry A.1 - F26 - Jacob MetskerLab: Calorimetry and Specific Heat

Lab: Calorimetry and Specific Heat — Unit test Answers

23 verified answers
1
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The decomposition of calcium carbonate, CaCO3(s) CaO(s) + CO2(g), has the following values for free energy and enthalpy at 25.0°C. G = 130.5 kJ/molH = 178.3 kJ/molWhat is the entropy of the reaction? Use G = H – TS.

Question illustration
A
160.3 J/(molK)
Option A
B
47.8 J/(molK)
Option B
C
160.3 J/(molK)
Option C
D
1,912 J/(molK)
Option D
2
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For the process 2SO2(g) + O2(g) 2SO3(g), S = –187.9 J/K and H = –198.4 kJ at 297.0 K are known. What is the entropy of this reaction? Use G = H – TS.

Question illustration
A
–386.3 J/K
B
–198.4 kJ/K
C
–187.9 J/K
D
–139.3 kJ
3

Which statement about spontaneous and nonspontaneous processes is correct?

A
Spontaneous processes are favored by a decrease in H, but nonspontaneous reactions are favored by an increase in H.
Option A
B
Spontaneous processes are favored by a decrease in S, but nonspontaneous reactions are favored by an increase in S.
Option B
C
An increase in S favors both spontaneous and nonspontaneous processes.
Option C
D
A decrease in H favors both spontaneous and nonspontaneous processes.
Option D
4

What is Gsystem for the system that is described by the following data?Hsystem = –232 kJ, T = 293 K, Ssystem = 195 J/KGsystem = Hsystem – TSsystem

Question illustration
A
–289 kJ
B
–175 kJ
C
256 kJ
D
56,903 kJ
5

A metal sample is heated and placed into the water in a calorimeter at room temperature. Which statement best describes how the calorimeter can be used to determine the specific heat capacity of the metal sample?

A
Energy transfers to the metal from the water and calorimeter until they are all at room temperature.
B
Energy transfers from the metal to the water and calorimeter until they are all at room temperature.
C
Energy transfers to the metal from the water and calorimeter until they all reach a single temperature.
D
Energy transfers from the metal to the water and calorimeter until they all reach a single temperature.
6

Two metal blocks that have slightly different temperatures are placed next to one another. After five minutes, they both have lower but equal temperatures. According to the law of conservation of energy, what most likely happened?

A
Energy was created inside the blocks.
B
Energy was destroyed inside the blocks.
C
Energy was absorbed into the blocks from outside the system.
D
Energy was transferred from the warmer block to the cooler block.
7

Which reaction is endothermic?

A
HCl + NaOH NaCl + H2O + 58 kJ
Option A
B
6CO2 + 12H2O + energy C6H12O6 + 6O2 + 6H2O
Option B
C
2Na + Cl2 2NaCl + energy
Option C
D
2C2H6 + 7O2 4CO2 + 6H2O + 2,502 kJ
Option D
8

Which best describes heat?

A
energy that is carried by electric and magnetic fields
B
energy that decreases as a car slows to a stop
C
energy that increases as a book is lifted to a higher shelf
D
energy that flows from a hot mug of tea to a cold hand
9

Nitrogen dioxide, NO2(g) (Hf = 33.84 kJ/mol), is decomposed according to the following reaction:What is the enthalpy change when 2.50 mol of nitrogen dioxide decomposes? Use .

Question illustration
A
13.5 kJ of energy released
B
13.5 kJ of energy absorbed
C
84.6 kJ of energy released
D
84.6 kJ of energy absorbed
10

Which direction does thermal energy flow in the following diagram?

Question illustration
A
Heat flows from the ice cream to the hand.
B
Heat flows from the hand to the ice cream.
C
The system is in a state of equilibrium.
D
The system is too cold for heat to move.
11

Complete combustion of a 0.350 g sample of a compound in a bomb calorimeter releases 14.0 kJ of heat. The bomb calorimeter has a mass of 1.20 kg and a specific heat of 3.55 J/(gi°C). If the initial temperature of the calorimeter is 22.5°C, what is its final temperature?Use .

Question illustration
A
19.2°C
B
25.8°C
C
34.2°C
D
72.3°C
12

Which statement best describes the direction of heat flow by conduction between two samples of the same material?

A
Heat flows from faster molecules to slower molecules when they are near.
B
Heat flows from faster molecules to slower molecules when they collide.
C
Heat flows from slower molecules to faster molecules when they are near.
D
Heat flows from slower molecules to faster molecules when they collide.
13

Ammonia, NH3 (Hf = –45.9 kJ), reacts with oxygen to produce water (Hf = –241.8 kJ) and nitric oxide, NO (Hf = 91.3 kJ), in the following reaction:What is the enthalpy change for this reaction? Use .

Question illustration
A
–902 kJ
B
–104.6 kJ
C
104.6 kJ
D
900.8 kJ
14

How should the baking of a pizza be categorized?

A
as an exothermic process because the dough releases heat
B
as an endothermic process because the dough releases heat
C
as an exothermic process because the dough absorbs heat
D
as an endothermic process because the dough absorbs heat
15

Which statement about enthalpy is true?

A
The enthalpy of formation for a pure element in its standard state is always positive.
B
The enthalpy of formation for a pure element in its standard state is always negative.
C
Enthalpy is a state function because its change depends only on initial and final conditions.
D
Enthalpy is not a state function because its change depends on the identities of the reactants and products.
16

Which is the best example of how electromagnetic energy is used?

A
a pot of boiling water on a gas stove
B
a patient receiving an X-ray in a hospital
C
a car burning gasoline to power the engine
D
a car of a roller coaster moving quickly down a slope
18

Which statement defines calorimetry?

A
the conservation of energy
B
a unit of energy that is used when calculating energy exchange
C
a device that is used to measure the heat that is gained or lost during a chemical change
D
the measurement of energy that is given off or absorbed in a physical or chemical process
20

A welding torch produces a flame by burning acetylene fuel in the presence of oxygen. This flame is used to melt a metal. Which energy transformation represents this process?

A
chemical energy into thermal energy
B
kinetic energy into potential energy
C
kinetic energy into electromagnetic energy
D
potential energy into chemical energy
21

How is enthalpy used to predict whether a reaction is endothermic or exothermic?

A
When the enthalpy of the reactants is higher than the enthalpy of the products, the reaction is endothermic.
B
When the enthalpy of the products is higher than the enthalpy of the reactants, the reaction is exothermic.
C
When the enthalpy change of the reaction is positive, the reaction is exothermic.
D
When the enthalpy change of the reaction is positive, the reaction is endothermic.
22

According to the law of conservation of energy, what will most likely happen in a closed system?

A
Energy will be exchanged along with matter.
B
Energy will be exchanged, but matter will not be exchanged.
C
Energy will be created along with matter.
D
Energy will be destroyed, but matter will not be destroyed.

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