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### Endothermic vs Exothermic

Posted: Wed Jan 29, 2020 2:33 pm
can someone confirm whether this is true: in the delta U = q + w , a negative value for q indicates an exothermic reaction within the system and a positive value indicates an endothermic one

### Re: Endothermic vs Exothermic

Posted: Wed Jan 29, 2020 3:18 pm
Yes, usually when a system gains heat, q will be a positive value.

### Re: Endothermic vs Exothermic

Posted: Wed Jan 29, 2020 4:31 pm
This is correct. A negative value of q indicates that the system lost heat. Thus, the reaction is exothermic. A positive value of q indicates that the system gained heat. Thus, the reaction is endothermic.

### Re: Endothermic vs Exothermic

Posted: Wed Jan 29, 2020 4:38 pm
Yes a +q means that the system is taking in heat therefore endothermic. a -q would mean that the system is losing heat and therefore exothermic. a +w means that the system is increasing energy by being compressed. a -w means that the system is losing energy through expansion.

### Re: Endothermic vs Exothermic

Posted: Wed Jan 29, 2020 6:24 pm
Yes this is correct, positive is always endothermic, negative is always exothermic

### Re: Endothermic vs Exothermic

Posted: Thu Jan 30, 2020 8:52 pm
Yeah you are right. Positive q means reaction is endothermic since the system gained heat. Negative q means reaction is exothermic since heat is released.

### Re: Endothermic vs Exothermic

Posted: Sat Feb 08, 2020 11:03 am
wow! Thanks for the responses!

### Re: Endothermic vs Exothermic

Posted: Sat Feb 08, 2020 11:48 am
A negative value of q corresponds to an exothermic reaction, and thus a positive value would indicate an endothermic reaction.

### Re: Endothermic vs Exothermic

Posted: Sat Feb 08, 2020 1:43 pm
Gaining heat would result in a positive q value whereas releasing heat would result in a negative q value.

### Re: Endothermic vs Exothermic

Posted: Sat Feb 08, 2020 9:47 pm
Yes, a negative is exothermic so then a positive would be endothermic. A way to remember it would be that exothermic is like "exit" and if something is exiting then it is leaving or losing something.

### Re: Endothermic vs Exothermic

Posted: Sat Feb 08, 2020 10:02 pm
If we look back at equilibrium reactions, we could predict which way a reaction must go in perspective of negative heat or positive heat energy. Exothermic processes involve the exertion of heat energy which makes the q a -q the same way -deltaH indicates an exothermic process. The same goes for endothermic process where there is a positive deltaH , indicating that heat is being absorbed, hence +q.