A student investigates the specific latent heat of fusion of ice.
The diagram shows the experimental setup used by the student.
Some of the ice in the funnel melts due to absorbing thermal energy from the surrounding air rather than from the immersion heater.
Suggest one modification the student can make to this setup or procedure to obtain a more accurate value for the specific latent heat of fusion of ice, and give a reason for your suggestion.
Suggestion: _____________________
Reason: _____________________
The table shows properties of four different phase-change materials (PCMs) used for thermal energy storage.
| Phase-change material | Melting point (∘C^\circ\text{C}∘C) | Specific latent heat of fusion (kJ/kg\text{kJ/kg}kJ/kg) |
|---|---|---|
| Paraffin wax | 373737 | 190190190 |
| Lauric acid | 434343 | 178178178 |
| Erythritol | 118118118 | 340340340 |
| Sodium acetate trihydrate | 585858 | 264264264 |
A manufacturer is designing a reusable hand-warmer. They want to choose a material from the table that will release the most thermal energy per kilogram when it undergoes a change of state from liquid to solid.
State and explain which material the manufacturer should choose.
Material: _____________________
Explanation: _____________________
Complete the sentence to explain the meaning of specific latent heat of vaporisation.
"Specific latent heat of vaporisation is the energy transferred when _____________________."