Question

8.00 g of aluminum at 200∘C and 19.0 g of copper are dropped into 50.0 cm3 of ethyl alcohol at 15.0∘C. The temperature quickly comes to 25.0 ∘C.

What was the initial temperature of the copper in ∘C?

Answer 1

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Quantity of heat loss by aluminium = m x c x dT
= 0.008* 913*(200 - 25) =  1278.2 J
.
Quantity of heat loss by copper = m x c x dT
= 0.019* 385*(T - 25) = 7.315 T - 182.875 J

Mass of ethyl alcohol = volume * density
= 0.000050 m^3 *789 = 0.03945 kg.

Quantity of heat gained by ethyl = mc dT
= 0.03945 * 2500*(25 - 15) = 986.25 J

heat lost = Heat gained
1278.2 J + 7.315 T - 182.875 J = 986.25 J


7.315 T = -109.075

T = - 14.91 ˚C

This shows that copper also gains heat.

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