## In which situation does delta U=0 and that q=-w

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Peter Dis1G
Posts: 97
Joined: Fri Sep 29, 2017 7:04 am

### In which situation does delta U=0 and that q=-w

Can anyone explain this? Thanks in advance!

CameronJohari1J
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Joined: Fri Sep 29, 2017 7:06 am
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### Re: In which situation does delta U=0 and that q=-w

The situation occurs when the system experiences isothermal change, thus delta U is zero. Subsequently, q=-w means that heat loss is equal work done on the system and visa versa is also true.

Peri Bingham 1G
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### Re: In which situation does delta U=0 and that q=-w

The situation would be an isothermal (constant temperature) reversible expansion.

Anna Li 2E
Posts: 21
Joined: Sat Jul 22, 2017 3:00 am

### Re: In which situation does delta U=0 and that q=-w

U stands for internal energy, so when delta U (the change in internal energy) is zero, that indicates that reaction is isothermal, a.k.a there is no change in temperature. This occurs when q, (also known as heat added to the system) is equal to -w. You can view this -w as the system expanding of its own volition, not due to any outside influence.

Peter Dis1G
Posts: 97
Joined: Fri Sep 29, 2017 7:04 am

### Re: In which situation does delta U=0 and that q=-w

By the way,is the reversible work equation also used for isothermal situation only?