Question

A very hot (750 ^oC) 270 g aluminum ingot is placed into an 0.75 kg steel pot with a lid. There is 250 g of water in the steel pot; both are initially at room temperature, 22^oC.

What is the final equilibrium temperature if the ingot is placed in the pot and then the top is quickly sealed?

If there is steam produced, how much is there?

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Answer 1

suppose final temp is T then assuming no heat loss.

heat released by aluminium = heat absorbed by water and steel

270 x 0.902 x (750 - T) = 750 x 0.120 x (T - 22) + (250 x 4.184 x (T - 22))

182655 - 243.54 T = 90 T - 1980 + 1046 T - 23012

T = 115 deg  

temp is more than 100 deg C so water will convert into steam.

suppose final temp is 100 deg

Heat present to convert water into steam.

Q = 182655 - 243.54 T -( 90 T - 1980 + 1046 T - 23012 )

Q = 69693 J

to convert into steam,

Q = m Lf

69693 = (m)(2260)

m = 30.8 grams

Ans: final temp = 100 deg C  

Steam produced = 30.8 grams