Question

If 1.10 g of steam at 100.0 degrees celsius condenses into 38.5 g of water, initially at 27.0 degrees celsius, in an insulated container, what is the final temperature of the entire water sample? Assume no loss of heat into the surroundings

Answer 1

heat lost by 100 C water + heat gained by cold water - heat lost by condensation =0

1.1*4.184*(Tf-100) +[38.5*4.184*(Tf-27)] - 1.1*2257 = 0
Solve for Tf.

You can do it another way if you wish.
First calculate how much the condensing steam will raise the T of cold water.
1.1*2257 = 2482.7 J released.
38.5*4.184*(Tf-27) = 2482.7
Tf = 42.41 THEN
heat lost by 1.1g steam @ 100C + heat gained by 41.41 C water = 0 and recalculate Tf EXCEPT, of course, Tinitial is 42.41 and not 27.0 C. Same answer is obtained.

Answer 2

Thank you! what is the 2257 from?

Answer 3

2257 is the heat of vaporization of water.