signs

$\Delta S = \frac{q_{rev}}{T}$

RenuChepuru1L
Posts: 58
Joined: Thu Jul 27, 2017 3:00 am

signs

When do we need to put a + in front of values to show that it is a positive value and when can we just leave it?

Posts: 71
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 1 time

Re: signs

The book (and it seems Lavelle does so as well but I haven't TRULY analyzed his lectures) seems to follow the notation whenever it talks about any matters regarding enthalpy, entropy, and Gibbs free energy. Specifically, the final answer for these questions such as the Delta H = +10 kJ/mol , etc. However, it may also help to use signs when doing temperatures in particular as well or anytime there is an instance of change using (final - initial).

Janet Nguyen 2H
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

Re: signs

I don't think you ever actually have to put +. It's probably just for emphasis/clarity

Yeyang Zu 2J
Posts: 58
Joined: Fri Sep 29, 2017 7:06 am

Re: signs

That's how Pro.Lavelle emphasizes in the lecture.
Positive signs mean gaining ENG and Negative signs mean giving ENG.
Probably for more accurate calculation and emphasize the direction of ENG flows.