## Heat and systems

isochoric/isometric: $\Delta V = 0$
isothermal: $\Delta T = 0$
isobaric: $\Delta P = 0$

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

### Heat and systems

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

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

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

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.