6.5 Specific latent heat

Question 1

When do you use specific latent heat of vaporization

Answer 1

liquid - gas

Question 2

When do you use specific latent heat of fusion

Answer 2

solid - liquid

Question 3

What happens if a substance in its liquid state is cooled

Answer 3

• solidify at same temp of melting point
• Particles bond together in rigid structure
• Latent heat is transferred to surroundings, as substance solidifies forming stronger bonds

Question 4

What is the specific latent heat of fusion of a substance

Answer 4

Energy needed to change the state of 1kg of the substance from solid to liquid at its melting point without changing temperature

Question 5

Whats the specific latent heat of fusion units

Answer 5

J/kg

Question 6

Equation for specific latent heat of fusion give units

Answer 6

SLHF (J/kg) = energy (J) / mass (kg)

Question 7

What happens to a substance in its gas state is cooled

Answer 7

• Condense at same temperature as its boiling point
• Latent heat transferred to surroundings as substance condenses into liquid, particles form new bonds

Question 8

What is the specific latent heat of vaporisation of a substance and give units

Answer 8

Energy needed to change the state of 1kg of a substance from liquid to vapour at its boiling point without changing temperature

J/kg

Question 9

Specific latent heat of vaporisation equation with units

Answer 9

SLHV (J/Kg) = energy (J) / mass (kg)

Question 10

Explain why both the specific latent heat and the specific heat capacity are needed for calculations in area of thermal physics

Answer 10

• Specific latent heat used to calculate changes of state
• Specific heat capacity is used to determine temperature change or heat energy needed for temperature change