00:01
In this question we have 1kg of water at 10 degrees celsius mixing with 10 degree of water at 30 degrees celsius at constant pressure.
00:10
So the final temperature, there are four parts in this question.
00:15
In parts a, we are interested in the final temperature at equilibrium.
00:21
So this is obvious, it should be 20 degrees celsius.
00:26
Then in parts b, we want to calculate the entropy of the system.
00:36
Okay, so delta s or system equals to delta s of the heating process and then plus the delta s of the cooling process.
00:49
Okay, because one, the one at 10 degrees celsius is heated up from 10 degrees celsius to 20 degrees celsius.
00:59
The water at 30 degrees celsius cools to 20 degrees celsius.
01:05
Okay, so delta s heating is equal to integral of eq over t.
01:15
This is mcpdd over t.
01:22
So and then mass is 1 kg and then cp is given as 4 .19.
01:29
Then natural log of initial temperature is 30 10 degrees celsius which is 283 final temperature is 293 kelvin so is we get 293 divide by 283 okay the delta s for cooling is equal to the q over t same steps and cpdt over t integrate from from 29303...