KVPY SA Exam 2014 Question Paper

Question : 68 of 80

Marks: +1, -0

An aluminum piece of mass 50 g initially at 300 °C is dipped quickly and taken out of 1 kg of water, initially at 30 °C. If the temperature of the aluminum piece immediately after being taken out of the water is found to be 160 °C, what is the temperature of the water then?
(Specific heat capacities of aluminum and water are 900 J kg

^{-1}

^{-1}

and 4200 J kg

^{-1}

^{-1}

, respectively.)

165 °C
45 °C
31.5 °C
28.5 °C

Validate

Solution:

Calorimetry principle
Heat lost = Heat gain
Heat loss by aluminum = Heat gain by water
50 × 10

^{–3}

× 900× (300 – 160) = 1 × 4200 × (T – 30)
6300 = 4200 (T – 30)
1.5 = T – 30
T = 31 .5ºC

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