1.1.3. Phase Changes and Latent Heat

It's the SI unit for Heat

• Watts

• Celsius

• Joules

• Nm

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)

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

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

• 50 100 cal

• 339 000 J

• 339 000 cal

• 50 100 J

Consider the following temperature-time graph when a solid is heated. which part of the graph involves latent heat of vaporization?

• Part I

• Part II

• Part III

• Part IV

To increase the temperature of an object we need to increase the _______ of the particles

• Average kinetic energy

• Average potential energy

What happens if the average potential energy of the particles is increased instead?

A beaker contains 150 mL of water at the boiling point. What extra thermal energy is required to vaporise it at 100°C?

• 3.38 × 10^8 J

• 3.38 × 10^5 J

• 5.01 × 10^4 J

• 5.01 × 10^7 J