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### change in internal energy

Posted: **Sat Mar 10, 2018 11:46 pm**

by **Stephanie tran 1J**

for examples involving calculating energy changes when heating an ideal gas, why do you have to separate the problem into two steps, step 1 being heating at constant volume to the final temperature, and step 2 being allowing the gas to expand isothermally?

### Re: change in internal energy

Posted: **Sat Mar 10, 2018 11:53 pm**

by **Emilie Hoffman 1E**

Because we don't have a way of calculating that kind of energy change at the same time because both of our equations deal with either a change in one or another.

### Re: change in internal energy

Posted: **Tue Mar 13, 2018 11:23 pm**

by **Rishi Khettry 1L**

Separating the steps allows us to perform two different calculations which would give us the final correct answer. It is impossible to calculate them simultaneously as there is not an equation we have learned to allow us to deal with both forms of energy change at the same time.

### Re: change in internal energy

Posted: **Fri Feb 08, 2019 3:35 am**

by **gwynlu1L**

I think it's better to think of these questions as 2 separate questions, not just 1 question. Reversible and irreversible reactions are not same, so their methods of solving are different. solving that kind of question is knowing that 2 separate experiments would be taking place.