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A quantity of hot water at 100oC is added to 400g of water at 10oC until the tem...


Question

A quantity of hot water at 100oC is added to 400g of water at 10oC until the temperature of the mixture is 60oC.

Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1]

Options

A) 200g

B) 320g

C) 400g

D) 500g


The correct answer is D.

Explanation:

Heat lost by hot water = Heat gained by cold water

M x 4200 x (100 - 60 = 0.4 x 4200 x (60 - 10)

4200m x 40 = 0.4 x 4200 x 50

40m = 0.4 x 50

m = \(\frac{0.4 \times 50}{40}\) = 0.5kg

= 500g


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Dicussion (1)

  • Heat lost by hot water = Heat gained by cold water

    M x 4200 x (100 - 60 = 0.4 x 4200 x (60 - 10)

    4200m x 40 = 0.4 x 4200 x 50

    40m = 0.4 x 50

    m = \(\frac{0.4 \times 50}{40}\) = 0.5kg

    = 500g

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