Define specific heat capacity .

The energy required to raise the temperature of one kilogram of a substance by one kelvin .

Good electrical conductors such as copper and lead are excellent conductors of heat because they have a .......... specific heat capacity

Good electrical conductors such as copper and lead are excellent conductors of heat because they have a low specific heat capacity

Define specific latent heat .

The thermal energy required to change the state of one kilogram of a substance without any change of temperature .

Distinguish between the specific latent heat of fusion and the specific latent heat of vaporisation .

Fusion = thermal energy to convert 1 kg of solid to liquid with no temperature change Vaporisation = thermal energy to convert 1 kg of liquid to gas with no temperature change

True or False? A substance's temperature rises while it changes state.

False. During a change of state there is no temperature change — the energy supplied (latent heat) goes into changing the arrangement of the molecules, not raising their temperature.

Why does boiling 1 kg of water need far more energy than melting 1 kg of ice?

Melting only needs enough energy to increase the molecular separation so molecules can flow past each other Boiling must fully separate the molecules until there are no longer forces of attraction between them, so it needs much more energy (about seven times more for water)

What is the aim of Core Practical 12: Calibrating a Thermistor?

To calibrate a thermistor so it can be used as a thermometer .

State the independent and dependent variables when calibrating a thermistor.

Independent variable = temperature (°C) Dependent variable = resistance of the thermistor (Ω)

The temperature is kept even throughout the beaker by continuously .......... the water.

The temperature is kept even throughout the beaker by continuously stirring the water.

How are the fixed resistor and ohm-meter connected to the thermistor?

The fixed resistor is connected in series with the thermistor The ohm-meter is connected in parallel across the thermistor to measure its resistance

How is the thermistor calibrated from the readings?

Plot a graph of resistance against temperature , then read off the resistance at any given temperature to use the thermistor as a thermometer.

True or False? The current should be left flowing through the thermistor between readings.

False. Turn the current off between readings to avoid heating in the wires (self-heating), which would raise the thermistor's temperature and distort the resistance readings.

Why should you allow time and stir the water before taking each reading?

To let the temperature reach equilibrium and stay even throughout the beaker, so the recorded temperature matches the actual temperature of the thermistor.

What does Core Practical 13: Investigating Specific Latent Heat aim to determine?

The specific latent heat of fusion of ice (the energy needed to melt 1 kg of ice with no temperature change).

Why is a second funnel of ice, with no heater , set up as a control?

Some ice melts due to energy from the surroundings , not the heater The control shows this background melting so it can be subtracted , leaving only the mass of ice melted by the heater

The mass of ice melted by the heater is found by .......... the control beaker's mass from the heated beaker's mass.

The mass of ice melted by the heater is found by subtracting the control beaker's mass from the heated beaker's mass.

How can you reduce energy losses to the surroundings in this experiment?

Apply lagging or insulation to the funnels and beakers, which reduces the energy transferred to the surroundings and improves accuracy.

True or False? While the ice is melting, the temperature of the ice rises.

False. During the change of state the temperature stays at 0 °C — all the energy supplied goes into melting the ice, not raising its temperature.

A LevelPhysicsEdexcelFlashcards9. ThermodynamicsThermal Energy Transfer

Thermal Energy Transfer (Edexcel A Level Physics): Flashcards

Exam code: 9PH0

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FrontSpecific Heat Capacity & Latent Heat
Define specific heat capacity.

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Cards in this collection (22)

Define specific heat capacity.
The energy required to raise the temperature of one kilogram of a substance by one kelvin.
State the equation for the heat energy, ΔE, needed to change a substance's temperature.
$Δ E = m c Δ θ$
Where Δ*E = change in heat energy (J), m = mass (kg), c = specific heat capacity (J kg^-1 K^-1) and Δθ* = change in temperature (K or °C)
Good electrical conductors such as copper and lead are excellent conductors of heat because they have a .......... specific heat capacity
Good electrical conductors such as copper and lead are excellent conductors of heat because they have a low specific heat capacity
Define specific latent heat.
The thermal energy required to change the state of one kilogram of a substance without any change of temperature.
Distinguish between the specific latent heat of fusion and the specific latent heat of vaporisation.
Fusion = thermal energy to convert 1 kg of solid to liquid with no temperature change
Vaporisation = thermal energy to convert 1 kg of liquid to gas with no temperature change
True or False?
A substance's temperature rises while it changes state.
False.
During a change of state there is no temperature change — the energy supplied (latent heat) goes into changing the arrangement of the molecules, not raising their temperature.
Why does boiling 1 kg of water need far more energy than melting 1 kg of ice?
Melting only needs enough energy to increase the molecular separation so molecules can flow past each other
Boiling must fully separate the molecules until there are no longer forces of attraction between them, so it needs much more energy (about seven times more for water)
State the equation for the energy needed to change the state of a substance.
$Δ E = L Δ m$
Where Δ*E = heat energy to change state (J), L = specific latent heat (J kg^-1) and Δm* = mass changing state (kg)
What is the aim of Core Practical 12: Calibrating a Thermistor?
To calibrate a thermistor so it can be used as a thermometer.
State the independent and dependent variables when calibrating a thermistor.
Independent variable = temperature (°C)
Dependent variable = resistance of the thermistor (Ω)
The temperature is kept even throughout the beaker by continuously .......... the water.
The temperature is kept even throughout the beaker by continuously stirring the water.
How are the fixed resistor and ohm-meter connected to the thermistor?
The fixed resistor is connected in series with the thermistor
The ohm-meter is connected in parallel across the thermistor to measure its resistance
How is the thermistor calibrated from the readings?
Plot a graph of resistance against temperature, then read off the resistance at any given temperature to use the thermistor as a thermometer.
True or False?
The current should be left flowing through the thermistor between readings.
False.
Turn the current off between readings to avoid heating in the wires (self-heating), which would raise the thermistor's temperature and distort the resistance readings.
Why should you allow time and stir the water before taking each reading?
To let the temperature reach equilibrium and stay even throughout the beaker, so the recorded temperature matches the actual temperature of the thermistor.
What does Core Practical 13: Investigating Specific Latent Heat aim to determine?
The specific latent heat of fusion of ice (the energy needed to melt 1 kg of ice with no temperature change).
Why is a second funnel of ice, with no heater, set up as a control?
Some ice melts due to energy from the surroundings, not the heater
The control shows this background melting so it can be subtracted, leaving only the mass of ice melted by the heater
The mass of ice melted by the heater is found by .......... the control beaker's mass from the heated beaker's mass.
The mass of ice melted by the heater is found by subtracting the control beaker's mass from the heated beaker's mass.
State the equation used to find the specific latent heat, L, and its rearranged form.
$Δ E = L Δ m$
Rearranged: $L = \frac{Δ E}{Δ m}$
Where Δ*E = energy supplied by the heater (J) and Δm* = mass of ice melted (kg)
How can you reduce energy losses to the surroundings in this experiment?
Apply lagging or insulation to the funnels and beakers, which reduces the energy transferred to the surroundings and improves accuracy.
True or False?
While the ice is melting, the temperature of the ice rises.
False.
During the change of state the temperature stays at 0 °C — all the energy supplied goes into melting the ice, not raising its temperature.
The experiment gives 330 000 J kg^-1 for the latent heat of fusion, but the accepted value is 334 000 J kg^-1. What is the percentage error?
$\frac{334 000 - 330 000}{334 000} \times 100 = 1.2 %$

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