Chapter 18 ( Hard )

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Questions and Answers

What happens to a system when thermal energy is transferred into it?

The internal energy of the system decreases.

The temperature of the system remains constant.

The heat energy of the system is negative.

The heat energy of the system is positive. (correct)

How is heat defined in the context of thermodynamics?

A measure of temperature change.

Energy due to the motion of molecules.

Energy that is stored in an object.

Energy in transfer to or from an object. (correct)

Which statement best describes the First Law of Thermodynamics?

The total amount of energy in an isolated system remains constant. (correct)

Temperature is a measure of a substance's heat content.

Heat flows spontaneously from cold to hot areas.

Energy can be created but not destroyed.

In which scenario is a system said to be in thermal equilibrium?

A cup of water at room temperature placed in the same temperature environment. Signup and view all the answers

What occurs to the temperature of a substance when it absorbs heat?

It may increase, decrease, or remain constant. Signup and view all the answers

If a cup of water at 20 °C is placed in a cooler environment at 10 °C, what happens to the heat energy?

The cup loses heat and decreases in temperature. Signup and view all the answers

Which of the following is true regarding heat transfer?

Heat always flows from hot to cold areas. Signup and view all the answers

What is the significance of heat in living organisms?

Heat provides energy necessary for life processes. Signup and view all the answers

What occurs when the temperatures of a system and its environment become equal?

Thermal equilibrium Signup and view all the answers

How is heat capacity defined in relation to temperature change?

The amount of heat energy required to change the temperature of a substance by 1 K Signup and view all the answers

What is indicated by a positive value for Q in thermodynamics?

Heat is gained by the system Signup and view all the answers

When does heat transfer typically occur?

When temperature differences exist Signup and view all the answers

If 2.00 kg of water is heated from 20.0 °C to 95.0 °C, what property of water is being utilized?

Specific heat capacity Signup and view all the answers

In the ratio of specific heats, if material A is warmed by 3 °C and material B by 4 °C, what can be concluded about their specific heats?

CA : CB = 4 : 3 Signup and view all the answers

Which of the following represents specific heat as expressed in units?

J/°C Signup and view all the answers

When raising the temperature of different copper blocks, which factor directly influences the amount of heat required?

Specific heat of copper Signup and view all the answers

What is the significance of achieving thermal equilibrium in natural processes?

It minimizes temperature fluctuations Signup and view all the answers

What is the term for the heat required to raise the temperature of 1 kg of a substance by 1 K without a phase change?

Specific heat capacity Signup and view all the answers

In the context of the ice to steam conversion, which process accounts for the largest amount of heat transfer?

Vaporizing water at 100 °C Signup and view all the answers

Which statement best describes the transfer of heat during a phase change such as melting?

Heat is absorbed without a change in temperature. Signup and view all the answers

What key factor determines the amount of heat required for a substance to change from one state to another, such as from ice to water?

The latent heat of fusion Signup and view all the answers

In a practical application, what role does vaporization play in heat management for living organisms?

It prevents overheating by absorbing excess heat. Signup and view all the answers

Which concept explains the heat transfer until thermal equilibrium is reached?

Heat conduction Signup and view all the answers

If the mass and temperature change of a substance are known, how can the specific heat capacity be calculated?

Heat gained divided by mass times temperature difference Signup and view all the answers

What happens to the temperature of a substance during a phase transition when heat is continuously added?

It remains constant until phase change is complete. Signup and view all the answers

In a perfectly insulated system, how does the first law of thermodynamics apply during the mixing of two liquids at different temperatures?

Total heat gained equals total heat lost. Signup and view all the answers

When a solid melts into a liquid, what phenomenon is primarily responsible for the energy transfer?

Latent heat of fusion Signup and view all the answers

What would be the expected final temperature when mixing equal masses of two identical liquids at different temperatures?

It is the average of the two initial temperatures. Signup and view all the answers

What is the energy exchange called when heat is added to cause a temperature increase in a material?

Thermal energy absorption Signup and view all the answers

In thermal equilibrium, what is the condition of two or more bodies with respect to temperature and heat flow?

They must be at the same temperature with no heat flow. Signup and view all the answers

What principle does the concept of latent heat rely on during phase transitions?

Energy is absorbed or released without a temperature change. Signup and view all the answers

What happens to the temperature of a substance during a phase change when heat is added?

The temperature remains constant. Signup and view all the answers

How does latent heat of fusion differ from latent heat of vaporization?

Fusion transitions a substance from solid to liquid, while vaporization transitions it from liquid to gas. Signup and view all the answers

What does the first law of thermodynamics state regarding heat energy?

The total energy of an isolated system remains constant. Signup and view all the answers

In the context of heat transfer, which mechanism is primarily responsible for transferring heat from a heated substance to its surroundings?

Convection Signup and view all the answers

Which statement accurately describes specific heat capacity?

It is the amount of heat required to change the temperature of a unit mass by 1°C. Signup and view all the answers

What is the effect of continuing to heat water at its boiling point?

The heat energy is used for the phase change to steam. Signup and view all the answers

In practical applications, how is latent heat beneficial in thermal systems?

It assists in controlling temperature during phase changes. Signup and view all the answers

Which of the following processes demonstrates thermal equilibrium principles?

Two objects at different temperatures placed in contact will eventually reach the same temperature. Signup and view all the answers

What is the latent heat of vaporization for a substance?

Heat required to change a substance from liquid to gas without temperature change. Signup and view all the answers

Study Notes

Heat

Heat is energy transferred to or from a system.
It’s symbol is Q
It is measured by Joules = J.
Heat flows from a higher to lower temperature.

First Law of Thermodynamics

Heat is a form of energy governed by the first law of thermodynamics.
Essential to life processes.

Specific Heat of Solids and Fluids

Heat capacity is the amount of heat required to change the temperature of a substance by one degree Celsius.
Specific heat is the heat capacity per unit mass.
Units of specific heat are (J/(kg \cdot K)) or (J/(kg \cdot °C)).

Latent Heat and Phase Transition

Latent heat is the energy absorbed or released during a phase change.
Latent heat of fusion is the energy required to change a substance from solid to liquid.
Latent heat of vaporization is the energy required to change a substance from liquid to gas.
Units of latent heat are (J/kg).

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Test your knowledge on heat, thermodynamics, and specific heat concepts. This quiz covers the basics of heat transfer, the first law of thermodynamics, and latent heat associated with phase transitions. Perfect for students looking to reinforce their understanding of these fundamental principles.