Latent Heat & Phase Change — A/L Physics

How do I practise Latent Heat & Phase Change?

1 question with a worked solution

1. How much thermal energy is required to completely melt 0.050 kg of ice at 0 °C and raise the resulting water temperature to 40 °C? (Specific latent heat of fusion of ice L_f = 3.34 × 10⁵ J kg⁻¹, specific heat capacity of water c = 4200 J kg⁻¹ K⁻¹)
   1. A) 8.4 kJ
   2. B) 25.1 kJ
   3. C) 16.7 kJ
   4. D) 33.5 kJ
   Check my answer

   Correct answer: B) 25.1 kJ

   Total heat Q = Q_melting + Q_heating = m L_f + m c ΔT = (0.050 kg × 3.34 × 10⁵ J kg⁻¹) + (0.050 kg × 4200 J kg⁻¹ K⁻¹ × 40 K) = 16,700 J + 8,400 J = 25,100 J = 25.1 kJ.

   Show worked solution

   Step 1: Melting heat: Q₁ = m L_f = 0.050 × 3.34 × 10⁵ = 16,700 J. Step 2: Heating heat: Q₂ = m c Δθ = 0.050 × 4200 × 40 = 8,400 J. Step 3: Total Q = 16,700 + 8,400 = 25,100 J = 25.1 kJ. Answer: 25.1 kJ.
   Modelled on: the A/L Physics examination pattern

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Where does Latent Heat & Phase Change fit in the syllabus?

Unit 4.5 · Year 1 · Term 2