Heat and systems

isochoric/isometric:
isothermal:
isobaric:

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Cyianna 2F
Posts: 34
Joined: Wed Nov 16, 2016 3:04 am

Heat and systems

Postby Cyianna 2F » Sun Jan 21, 2018 11:44 pm

How can you tell whether or not heat is being transferred to the system or from the system?

Minie 1G
Posts: 63
Joined: Fri Sep 29, 2017 7:04 am

Re: Heat and systems

Postby Minie 1G » Sun Jan 21, 2018 11:47 pm

Heat transfers from a higher point of temperature to a lower one. So look at a problem and determine if the system losing heat or gaining heat.

Andrea Grigsby 1I
Posts: 60
Joined: Fri Sep 29, 2017 7:03 am

Re: Heat and systems

Postby Andrea Grigsby 1I » Sun Jan 21, 2018 11:48 pm

if you have deltaH/Q, you can look at the sign it has
-deltaH means that energy is released by the system (exothermic; the system is losing energy, thus the minus sign) and so energy is being transfered from the system to the surroundings. eg combustion reactions
+deltaH means that energy is gained by the system (endothermic) and so energy is being transfered to the system from the surroundings. eg the melting of ice

juchung7
Posts: 44
Joined: Fri Sep 29, 2017 7:05 am

Re: Heat and systems

Postby juchung7 » Sun Jan 21, 2018 11:49 pm

When heat is transferred out of a system, heat is lost so the q value is negative (exothermic). When heat is transferred into a system, heat is gained so the q will be positive (endothermic). I hope this answers your question.


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