## Entropy V.S Enthalpy QUestion

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

504999222
Posts: 25
Joined: Tue Nov 13, 2018 12:18 am

### Entropy V.S Enthalpy QUestion

I'm not sure if this always applies, but if enthalpy is negative and the entropy is negative, would that mean both are spontaneous?
If so then would that same question apply if both enthalpy and entropy were positive? Or if one is positive and the other is negative?

Aman Sankineni 2L
Posts: 103
Joined: Fri Aug 30, 2019 12:17 am

### Re: Entropy V.S Enthalpy QUestion

https://opentextbc.ca/introductorychemi ... erature-2/

Ryan Lee 1E
Posts: 50
Joined: Sat Aug 17, 2019 12:16 am

### Re: Entropy V.S Enthalpy QUestion

Spontaneity would be determined by free energy, whose equation is deltaG = deltaH - TdeltaS. It's not just if enthalpy (H) or entropy (S) is a certain value, but the both in combination would have to work together to make something spontaneous. On that note, a positive deltaS indicates that entropy is increasing, which means it would contribute to deltaG being spontaneous (not what you said about entropy being negative). Typically for something to be spontaneous, deltaH would have to be negative exothermic and deltaS would have to be positive increasing entropy. In context, this also makes sense since since entropy increasing means the system is approaching equilibrium, which is something a system wants to do.

Louise Lin 2B
Posts: 97
Joined: Sat Aug 17, 2019 12:15 am

### Re: Entropy V.S Enthalpy QUestion

Not necessarily, spontaneous and nonspontaneous would have to depend on how large the values of entropy and enthalpy are compared to each other. For example, if both entropy and enthalpy were negative, it is still possible for the overall reaction to be nonspontaneous if the value of entropy multiplied with temperature (-TdeltaS) is larger than a negative enthalpy.