Hey,
Having a bit of a dilemma with the CGP revision guide for this module.
Working out total entropy change. I would normally do this for the reaction by working out products - reactants. This has always worked before.
THE CGP guide introduces a concept whereby you have to take into account the surroundings too. So the total entropy change = entropy change in the system (calculated like above) + entropy change in the surroundings (calculated by minus delta H over T).
We've never been taught this :/ Have any of you guys? We're trying to work out whether this would ever be used, we've done the mock exams and it's never asked for an entropy value in this way. And I can't work out how to distinguish which method to use. Enlighten me please!!!