Question

[E] Simple Problems
1. 0-300 kg of water at 15°C are mixed with 0-500 kg of water at 30°C. What is the resulting temperature?
[Ans. 24:38°C​

Answer 1

Answer:

Heat gained by ice = heat lost by the water.

The change in temperature for the water is:

50 - 6.7 =43.3°C

The change in temperature of ice is:

6.7°C

Q=mcΔT where Q is the quantity of heat gained or lost, m the mass of the substance, c the specific heat capacity of water and ΔT the temperature change.

Heat gained by ice is: mLf + mcΔT where lf is the latent heat of fusion and c the specific heat capacity of water.

In this question we are looking for the Lf thus it is not known.

Substituting what we is given in the formulae we get :

0.15Lf + 0.15 × 4186 × 6.7 =0.15Lf + 4206.93

Heat lost by the water is:

0.30 ×4186 × 43.3 =54376.14Joules

54376.14 = 0.15Lf + 4206.93

0.15Lf = 54376.14 - 4206.93

0.15Lf = 50169.21

Lf =50169.21 ÷ 0.15 =334461.40joules/Kg

Explanation:

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