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A Level Specific Heat Capacity Questions

Q10. In an experiment to measure the temperature of the flame of a Bunsen burner, a lump of copper of mass 0.12 kg is heated in the flame for several minutes. The copper is then transferred quickly to a beaker, of negligible heat capacity, containing 0.45 kg of water, and the temperature rise of the water measured.

( specific heat capacity of water = 4200 J kg - 1 K - 1

specific heat capacity of copper = 390 J kg - 1 K - 1)

(a) If the temperature of the water rises from 15 °C to 35 °C, calculate the thermal energy gained by the water.

ΔQ = mcΔθ

ΔQ = 0.45 × 4200 × (35 − 15)

ΔQ = 3.8 × 104 J (3.78 × 104 J )

(2 marks)

(b)

(i) State the thermal energy lost by the copper, assuming no heat is lost during its transfer.

3.8 × 104 J

(ii) Calculate the fall in temperature of the copper.

ΔQ = mcΔθ

3.8 × 104 = 0.12 × 390 × Δθ

Δθ = 812 K

(use of ΔQ =3.78 x 104 J gives Δθ = 808 K - both round to 810K)

(iii) Hence calculate the temperature reached by the copper while in the flame.

(812 + 35) = 847 ºC

(use of 808 gives 843 ºC)

(4 marks)

(Total 6 marks)