Latent heat Heat of fusion Heat of vaporization – Problems and Solutions

4 Latent heat Heat of fusion Heat of vaporization – Problems and Solutions

1. Calculate the amount of heat added to 1 gram gold to change phase from solid to liquid. The heat of fusion for gold is 64.5 x 10³ J/kg.

Known :

Mass (m) = 1 gram = 1 x 10^-3 kg

Heat of fusion (L_F) = 64.5 x 10³ J/kg

Wanted : Heat (Q)

Solution :

Q = m L_F

Q = (1 x 10^-3 kg)(64.5 x 10³ J/kg)

Q = 64.5 Joule

2. Calculate the amount of heat released by 1 gram mercury to change phase from liquid to solid. Heat of fusion for mercury is 11.8 x 10³ J/kg.

Known :

Mass (m) = 1 gram = 1 x 10^-3 kg

Heat of fusion (L_F) = 11.8 x 10³ J/kg

Wanted : Heat (Q)

Solution :

Q = m L_F

Q = (1 x 10^-3 kg)(11.8 x 10³ J/kg)

Q = 11.8 Joule

3. Determine the amount of heat absorbed by 1 kg water to change phase from liquid to vapor (steam). Heat of vaporization for water = 2256 x 10³ J/kg

Known :

Mass (m) = 1 kg

Heat of vaporization (L_V) = 2256 x 10³ J/kg

Wanted : Heat (Q)

Solution :

Q = m L_V

Q = (1 kg)(2256 x 10³ J/kg)

Q = 2256 x 10³ Joule

4. Determine the amount of heat released by nitrogen to change phase from vapor to liquid. Heat of vaporization for nitrogen = 200 x 10³ J/kg

Known :

Mass (m) = 1 gram = 1 x 10^-3 kg

Heat of vaporization (L_V) = 200 x 10³ J/kg

Known : Heat (Q)

Solution :

Q = m L_V

Q = (1 x 10^-3 kg)(200 x 10³ J/kg)

Q = 200 Joule

1. Converting temperature scales
2. Linear expansion
3. Area expansion
4. Volume expansion
5. Heat
6. Mechanical equivalent of heat
7. Specific heat and heat capacity
8. Latent heat, heat of fusion, heat of vaporization
9. Energy conservation for heat transfer