alleryStart learning →If 2500 kJ of heat is just enough to melt 3.0 kg of an unknown substance, what is that substance's latent heat of fusion?
A280 kJ/kg
B570 kJ/kg
C830 kJ/kg
D7500 kJ/kg
Answer & Solution
Correct answer: C. 830 kJ/kg
1. Rearranging Q = mLf for the latent heat of fusion gives Lf = Q divided by m.
2. Substitute Q = 2500 kJ and m = 3.0 kg.
3. Dividing gives Lf = 833 kJ/kg, which rounds to 830 kJ/kg.
4. 7500 kJ/kg would result from multiplying instead of dividing.
5. 280 and 570 kJ/kg do not come from this data at all.
6. So 830 kJ/kg is correct.
_Source: OpenStax Physics (CC BY 4.0), Ch 11 "Thermal Energy, Heat, and Work", section 11.3 Phase Change and Latent Heat_
Keep practising Thermal Energy, Heat, and Work
Browse all Thermal Energy, Heat, and Work questions for GCE O-Level (Singapore), or explore more Physics topics.
Related questions
A 3.00 kg sample at its boiling point is entirely boiled away by 5360 kJ of heat. What is How much energy is required to melt 7.00 kg of aluminum already at its melting point? Use In which phases of matter can the particles change position relative to their neighbours?How is latent heat defined?How much energy is needed to melt 2.00 kg of ice already at 0 degrees Celsius? Use Lf(wateHow much heat is needed to vaporize 1.000 kg of water already at 100 degrees Celsius? Use How much heat is needed to melt 1.000 kg of ice already at 0 degrees Celsius? Use the lateWhat is the name for a direct phase change from solid to gas?