## Endothermic vs Exothermic

$\Delta U=q+w$

Ryan_K_1K
Posts: 51
Joined: Wed Nov 14, 2018 12:18 am

### Endothermic vs Exothermic

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

Veronica_Lubera_2A
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### Re: Endothermic vs Exothermic

Yes, usually when a system gains heat, q will be a positive value.

Wendy 1E
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### Re: Endothermic vs Exothermic

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.

Andrew Liang 1I
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Joined: Fri Aug 30, 2019 12:18 am

### Re: Endothermic vs Exothermic

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.

alex_4l
Posts: 109
Joined: Thu Sep 26, 2019 12:18 am

### Re: Endothermic vs Exothermic

Yes this is correct, positive is always endothermic, negative is always exothermic

Posts: 50
Joined: Tue Nov 05, 2019 12:18 am

### Re: Endothermic vs Exothermic

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.

Ryan_K_1K
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Joined: Wed Nov 14, 2018 12:18 am

### Re: Endothermic vs Exothermic

wow! Thanks for the responses!

Posts: 103
Joined: Sat Aug 17, 2019 12:18 am

### Re: Endothermic vs Exothermic

A negative value of q corresponds to an exothermic reaction, and thus a positive value would indicate an endothermic reaction.

Jessica Kwek 4F
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### Re: Endothermic vs Exothermic

Gaining heat would result in a positive q value whereas releasing heat would result in a negative q value.

Emily Lo 1J
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Joined: Thu Sep 19, 2019 12:16 am

### Re: Endothermic vs Exothermic

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.

Posts: 97
Joined: Tue Feb 12, 2019 12:15 am

### Re: Endothermic vs Exothermic

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.

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