Phase Changes and Latent Heat

It's the amount of heat required to change the state (gas,liquid, solid) of a unit of material

• Latent Heat

• Specific Heat

• Temperature

• Q

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)

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Latent heat is

• the heat absorbed or released at a boiling process during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase of 1 kg object

• the heat absorbed or released by an object to increase or decrease its temperature by 1 degree Celcius

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

specific latent heat of vaporisation is

• the amount of heat required to change 1 kg of the substance from the solid to liquid phase without change in temperature

• the amount of heat required to change 1 kg of the substance from the liquid to gaseous phase without change in temperature

• the amount of heat required to change the temperature 1 kg of the substance by 1 degree Celcius

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Water molecules have the greatest kinetic energy in

• Ice at 0 ⁰C

• Water at 90 ⁰C

• Water at 373 K

• Steam at 150 ⁰C

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The graph shows the cooling curve of a substance. At which stages the specific latent heat released?

• AB and CD

• BC and DE

• AB and EF

• BC and CD

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Calculate the energy absorbed by 30 g of 100 ⁰C water that is turned into 100 ⁰C.

• 67 800 J

• 6 7800 J

• 678 J

• 67.8 J

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• 16.1 XundefinedJ

• 16.8 XundefinedJ

• 15.1 Xundefinedcal

• 16.8 Xundefinedcal

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The graph shows the cooling curve of a substance.
The specific latent heat released at stages?

• CD and FG
• DE and EF
• EF and FG
• DE and FG