Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

Hey everyone!!

I need some clarification on entropy; when are we supposed to add entropies vs. subtract entropies?

Do we add only when a change of volume as change of temperature is given (& no equation is given)? And subtract if an equation w/ the entropies of an equation w/ products & reactants given?

Thank you!!

martha-1I
Posts: 76
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Adding vs. Subtracting entropies

When we are given an equation and asked to calculate change in entropy, we do so by adding up all the entropies on the product side and subtracting them from the sum of the entropies from the reactant side.
The equation is $\Delta S$=$\sum \Delta$Sproducts - $\sum \Delta$Sreactants