Chapter 5: Thermal Energy Flashcards

Thermal energy, Conduction, Convection, Radiation, Internal energy, Heat capacity, Latent heat, Boiling and Evaporation

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1
Q

How is thermal energy transfered?

A

From a region of high temperature to a region of low temperature

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2
Q

What is thermal equilibrium?

A

A state where there is no net movement of thermal energy

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3
Q

How can thermal energy be transferred?

A

Via conduction, convection and radiation

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4
Q

How does conduction transfer heat?

A

Thhrough a medium without any flow of medium

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5
Q

What states does conduction take place, and in which states is conduction the fastest?

A

Solids (fastest), Liquids, and Gases (slowest)

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6
Q

Why is heat conducted better in metals?

A

The presence of free electron diffusion aids in conduction of heat

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7
Q

How is equilibrium reached in conduction?

A

Molecules with more energy collide into molecules with less energy, transferring kinetic energy until equilibrium is reached

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8
Q

How does density affect conduction rate?

A

The closer particles are to each other (denser), the faster conduction takes place

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9
Q

How does convection transfer heat?

A

Usage of convection currents in fluids. When a fluid is heated from below, that fluid will expand become less dense and rise, causing the denser fluid to sink onto the heat source, heating that fluid up

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10
Q

What states of matter does convection take place in?

A

Liquids and Gases

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11
Q

How does radiation transfer heat?

A

Transfers energy in the form of electromagnetic waves, without the use of a medium

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12
Q

What can be done to increase rate of absorption of heat via radiation?

A

Increasing surface area, making the surface dull, rough and black

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13
Q

What can be done to decrease rate of absorption of heat via radiation?

A

Decreasing surface area, making surface shiny, smooth and silver

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14
Q

How is temperature of surroundings related to rate of radiation?

A

Te higher the temperature of the object relative to its surroundings, the greater the rate of radiation

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15
Q

What is internal energy?

A

The total energy of all particles in the substance

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16
Q

What does internal energy consist of?

A

Kinetic and Potential Energy

17
Q

Which internal energy increases when temperature increases?

A

Kinetic energy

18
Q

What is heat capacity?

A

The amount of thermal energy required to raise the temperature of a substance by 1 degree Celcius or Kelvin

19
Q

How is heat capacity calulcated?

A

Heat Capacity (c) = Amount of Energy in Joules (Q) / Change in Temperature (Delta Q)

20
Q

What is specific heat capacity?

A

The amount of thermal energy required to raise the temperature of a substance by 1 degree Celcius or Kelvin per unit mass of substance

21
Q

How is specific heat capacity calculated?

A

Specific Heat Capacity (c) = Amount of Energy in Joules (Q) / (mass in kg (m) x Change in temperature (Delta Q))

22
Q

How can thermal energy supplied to a substance be found using its mass, change in temperature and its specific heat capacity?

A

Q = m x c x Delta Q

23
Q

What is Latent Heat?

A

The amount of energy released or absorbed by a substance during a change of state without a change in temperature

24
Q

What is the Latent heat of Fusion?

A

The amount of thermal energy needed / released to change a substance from solid to liquid or vice versa without a change in temperature

25
Q

What is Latent heat of Vaporisation?

A

The amount of thermal energy needed / released to change a substance from liquid to gaseous or vice versa without a change in temperature

26
Q

How can specific latent heat be calculated?

A

Specific Latent Heat = Latent Heat / mass of substance

27
Q

What are some differences between boiling and evaporation?

A

Boiling: At a particular temperature, Temperature remains constant, takes place throughout the liquid, bubbles are formed, fast process, external thermal energy is needed
Evaporation: At any temperature, Temperature may change, takes place on the surface of a liquid, no bubbles are formed, slow process, no external energy is needed

28
Q

What are some factors that affect evaporation?

A

Temperature - Directly Related
Humidity - Inversely Related
Surface Area of Liquid - Directly Related
Pressure - Inversely Related
Movement of Air - Directly Related
Boiliing Point of Liquid - Inversely Related