AnswersVJSHS - Chemistry Full YearUnit Test

Unit Test — Unit test Answers

25 verified answers3 views
1
Free Preview

Consider the following intermediate chemical equations.How will oxygen appear in the final chemical equation?

Question illustration
A
as a product
Option A
B
as a reactant
Option B
C
O(g) as a product
D
2O(g) as a reactant
2
Free Preview

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
3

What explains the key difference between a bomb calorimeter and a coffee cup calorimeter?

A
A bomb calorimeter is 10 times larger but works the same way.
B
A bomb calorimeter measures heat for liquid products only.
C
A bomb calorimeter has a separate chamber to hold substances and can even measure heat gain or loss for reactions that do not occur in water.
D
A bomb calorimeter can measure heat gain or loss in gaseous reactions but is not useful for reactions that occur at high pressures and temperatures.
4

Consider the following intermediate chemical equations. The overall chemical equation is . To calculate the final enthalpy of the overall chemical equation, which step must occur?

Question illustration
A
Reverse the first equation, and change the sign of the enthalpy. Then, add.
B
Reverse the second equation, and change the sign of the enthalpy. Then, add.
C
Multiply the first equation by three, and triple the enthalpy. Then, add.
D
Divide the third equation by two, and double the enthalpy. Then, add.
5

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.
6

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
7

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
8

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.
9

Which describes the enthalpy change associated with an endothermic reaction?

A
It is negative because the enthalpy of the products is greater than the enthalpy of the reactants.
B
It is positive because the enthalpy of the products is greater than the enthalpy of the reactants.
C
It is negative because the enthalpy of the reactants is greater than the enthalpy of the products.
D
It is positive because the enthalpy of the reactants is greater than the enthalpy of the products.
10

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
11

Which energy graph represents the nonspontaneous transition of graphite into diamond?

A
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts low on the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down a short distance, and levels out.
Option A
B
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down sharply, and levels out below the initial starting point.
Option B
C
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a small amount, then curves down to level out below the initial starting point.
Option C
D
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a moderate amount, then curves down sharply to level out below the initial starting point.
Option D
12

Which statement best applies collision theory to preventing a dangerous reaction from occurring?

A
Store the reactants together at a low pressure.
B
Keep all sparks or flames away from the reactants.
C
Store the reactants together at a low temperature.
D
Keep the reactants in separate containers.
13

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
14

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
15

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
16

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
17

A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A
It increased the number of molecular collisions.
B
It decreased the number of molecular collisions.
C
It decreased the space between the molecules and lowered the reaction rate.
D
It increased the space between the molecules and increased the reaction rate.
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
19

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
20

What happens as the activation energy increases?

A
The pressure of the system decreases.
B
The kinetic energy of colliding molecules changes.
C
The reactant surface area decreases.
D
The reaction begins to slow down.

Did you find these answers helpful?