A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g-1°C-1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample. Be sure your answer is rounded to 2 significant digits.

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Chemistry

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8 November, 17:07

A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g-1°C-1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample. Be sure your answer is rounded to 2 significant digits.

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Jorge Carr · Answer 1

T₁ = 90°C

Explanation:

Let system 1 = > brass sample & system 2 = > water

∑q = 0 = q₁ + q₂ = (mcΔT) ₁ + (mcΔT) ₂

= [ (52.9g) (0.375j/g°C) (18.4°C - T₁) ]₁ + [ (100.0g) (4.184j/g°C) (18.4°C - 15°C) ]₂ = 0

=> 19.83 (18.4°C - T₁) + 1423 = 0 = > 365 - 19.83T₁ + 1423 = 0

=>19.83T₁ = 1788 = > T₁ = (1788/19.83) °C = 90°C