Latent Heat Calculations

Latent Heat

4.3 Specifc Latent Heat

Open Ended

According to video, what make the ice melted?

4.3 Specific Latent Heat

4.3.1 Explain latent heat. 

4.3.2 Define: 

(i) specific latent heat

(ii) specific latent heat of fusion

(iii) specific latent heat of evaporization

4.3.4 Communicate to explain the applications of specific latent heat in daily life.

Latent heat

• Specific latent heat, l of a substance is the quantity of heat, Q that is absorbed or released during a change of phase of 1 kg of the substance without any change in its temperature.

Specific latent heat of fusion, l_f

The quantity of heat, Q that is absorbed during melting or the quantity of heat released during freezing of 1 kg of the substance without any change in temperature

Specific latent heat of vaporisation, l_v  

The quantity of heat, Q that is absorbed during boiling or the quantity of heat released during condensation of 1 kg of the substance without any change in temperature.

Multiple Choice

In which phase is substance exist in a form of solid and liquid.

• AB

• BC

• CD

• DE

• EF

Multiple Choice

Which phase is substance exist in a form of liquid only.

• AB

• BC

• CD

• DE

• EF

Multiple Choice

What would be the effect on the particles if more heat is supplied to the system?

• They would slow down
• They would stop moving
• They would speed up
• There would be no effect

Multiple Choice

What is the formula to calculate specific latent heat of vaporisation?

• $$l=\frac{Q}{m}$$

• c = Q/(mΔƟ)

• Q = mcΔƟ

• $$Q=ml$$

Multiple Choice

The heat absorbed by melting a solid is known as

• latent heat of fusion

• latent heat of solid

• latent heat of liquid

• latent heat of vaporisation

Multiple Choice

This formula is used to find the amount of heat (energy) neccesary when there's a phase change

• Q= (h)(ΔT)

• Q=(m)(L)

• Q=(m)(c)(ΔT)

• Q=(k)(A)(dT)

Multiple Choice

It's the SI unit for Heat

• Watts

• Celsius

• Joules

• Nm

Multiple Choice

The diagram shows a cooling curve for ice. Which line represents the ice freezing?

• A

• B

• C

• D

• E

Multiple Choice

The diagram shows a cooling curve for ice. Which line represents the ice in a liquid state (water)?

• A

• B

• C

• D

• E

Multiple Choice

Why are lines B and D flat?

• The ice is melting

• The ice is freezing

• All of the thermal energy is used to break the bonds

• They stopped the stopwatch

• They stopped heating the ice.

Multiple Choice

The diagram shows a heating curve for ice. Which line represents the ice melting?

• A

• B

• C

• D

• E

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