Here\'s the overall question... ----- You probably know that when two objects at

Question

Here's the overall question...
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You probably know that when two objects at different temperaturesare brought into contact, heat always travels from the hotterobject to the colder object; never the reverse.

Imagine that you have two iron blocks, one with amass 207 g at a temperature of25.4 oC, and another with a mass203 g at a temperature of 143oC. The two blocks are brought into contact with eachother in an insulated container.

Specific heat of iron = 0.444JK-1g-1

What is the sign of the entropy change for the heat transfer (enterpositive or negative) that takes place?

Sign of entropy change =

What is the final temperature of the two ironblocks?

Final temperature = oC

What is the entropy change for the heat transfer described in thisquestion?

Entropy change = JK-1
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I know how to find the first two questions. It's the last onethat's stumping me.

"What is the entropy change for the heat transfer described in thisquestion?"


Any help here?

Thanks!

Explanation / Answer

S = mCsln (Tf / Ti) Since you know the final temperature and initial temperatureof the two blocks of iron, first calcualte the entropy change foreach block seperately and then add them to get total change inentropy. For 207g of iron block allpy      S207g =mCsln (Tf / Ti) For 203g of iron block apply S203g = mCsln (Tf /Ti) Hence, total entropy is S = S207g +S203g

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