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WorksheetsThermochemistry
Total questions: 22
Worksheet time: 28mins
How can the heat of reaction be determined from the standard heats of formation of the reactants and products?
Add the standard heats of formation of the reactants and the products.
Multiply the standard heats of formation of the reactants by that of the products.
Subtract the standard heats of formation of the reactants from that of the products.
Subtract the standard heats of formation of the products from that of the reactants.
.
Is the flow of energy during vaporizing more like the flow of energy during melting or during freezing?
It is more like the flow of energy during melting because both processes absorb energy.
It is more like the flow of energy during freezing because both processes absorb energy.
It is more like the flow of energy during melting because both processes release energy.
It is more like the flow of energy during freezing because both processes release energy.
.
A calorimeter holds 125 g water at 22.0°C. A 45 g sample of silver at 130.0°C is added to the water, and the final temperature of the water and silver is 24.2°C. The specific heat of water is 4.18 J/g°C. What is the specific heat of silver?
0.241 J/g°C
2.16 J/g°C
51.8 J/g°C
558 J/g°C
4.
What type of energy flows naturally from a hot object to a cooler object?
potential energy
light energy
thermal energy
mechanical energy
.
How does an exothermic reaction compare with an endothermic reaction?
Both changes absorb energy as reactants become products.
Both changes release energy as reactants become products.
An exothermic reaction absorbs energy, and an endothermic reaction releases energy.
An endothermic reaction absorbs energy, and an exothermic reaction releases energy.
What happens to the surroundings when a substance freezes?
The surroundings get cooler.
The surroundings get warmer.
The surroundings transfer thermal energy to the substance.
The substance absorbs thermal energy from the surroundings.
7.
During which physical changes does a substance absorb energy from its surroundings?
as it melts, freezes, and increases in temperature
as it vaporizes, condenses, and decreases in temperature
as it melts, vaporizes, and increases in temperature
as it freezes, condenses, and decreases in temperature
.
How does the flow of energy during freezing compare with the flow of energy during melting?
In each process, energy flows into the material undergoing the change.
In each process, energy flows out of the material undergoing the change.
Energy flows into a substance that is freezing and out of a substance that is melting.
Energy flows out of a substance that is freezing and into a substance that is melting.
.
A hot piece of metal is placed into cooler water. Which statement describes how the second law of thermodynamics relates to this process?
The temperature change of the metal is equal to the temperature change of the water.
The amount of energy lost by the metal is equal to the amount of energy gained by the water.
Energy flows from the metal to the water until they are at the same temperature.
Energy flows from the water to the metal until they are at the same temperature.
.
Which statement best describes the relationship between the system and the surroundings?
The system is found in the surroundings but is not included as part of the surroundings.
The system is found in the surroundings and is part of the surroundings.
The system is found around the surroundings and includes the surroundings.
The system is found around the surroundings but does not include the surroundings.
.
A calorimeter should be well insulated to prevent which of the following from entering or leaving the system?
light energy
thermal energy
solids
gases
2.
A change occurs that raises the temperature of the container in which it happens. What is the best term to describe the change?
chemical
physical
exothermic
endothermic
3.
What happens during an exothermic reaction?
One or more new substances form, and energy is released.
One or more new substances form, and energy is absorbed.
A substance changes state, and energy is released.
A substance changes state, and energy is absorbed.
.
What observation would indicate that an endothermic reaction is occurring in a beaker?
The beaker glows.
The contents of the beaker become a solid.
The contents of the beaker change color.
The beaker feels cool.
How is thermal energy involved when a substance freezes?
Thermal energy flows into the substance from the surroundings.
Thermal energy flows from the substance into the surroundings.
Thermal energy is produced by the substance.
Thermal energy is destroyed by the substance.
.
Which term is best used to identify a group of interconnected parts that are surrounded by a barrier?
system
surroundings
endothermic
exothermic
system
.
Which statement correctly describes an endothermic process?
Energy is absorbed.
Energy is released.
Matter is absorbed.
Matter is released.
.
How does thermal energy naturally flow?
from an area of high density to an area of low density
from an area of high specific heat to an area of low specific heat
from an area of high mass to an area of low mass
from an area of high temperature to an area of low temperature
9.
What term includes everything other than what is under study?
system
room
universe
surroundings
0.
Which of the following is a statement of the first law of thermodynamics in relation to chemical and physical changes?
Energy flows naturally from the system to the surroundings.
Energy cannot be created or destroyed.
Energy flows naturally from high temperature to low temperature.
The energy released is greater than the energy absorbed.
Where is chemical potential energy stored?
in atoms
in thermal energy
in chemical reactions
in chemical bonds
Use the standard heats of formation to calculate the heat of reaction for the complete combustion of ethane.
2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g)
3,194.0 kJ
46.0 kJ
–551.7 kJ
–2,855.6 kJ
