## irreversible and reversible

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

Kirsty Star 2H
Posts: 48
Joined: Fri Sep 28, 2018 12:24 am

### irreversible and reversible

So for an irreversible reaction where pressure is constant, the equation is w = -PΔV and for a reversible reaction where pressure is constantly becoming smaller, the equation is w = -nRTln(v2/v1). Is this right?

Also, where does the equation ΔU = 3/2nRΔT come from?

Mindy Kim 4C
Posts: 65
Joined: Fri Sep 28, 2018 12:25 am

### Re: irreversible and reversible

Yes, the two equations you stated are both correct.
Dr. Lavelle mentioned the third equation briefly, but basically, the internal energy of an ideal gas is dependent on temperature. The 3/2 in the equation comes from the translational motion along the x,y, and z axes.

BenJohnson1H
Posts: 68
Joined: Fri Sep 28, 2018 12:17 am

### Re: irreversible and reversible

And likewise, in some cases this fraction will be 5/2 or 7/2 depending on the molecules. The text book has a more detailed explanation.

Summer de Vera 2C
Posts: 65
Joined: Fri Sep 28, 2018 12:16 am

### Re: irreversible and reversible

In general, are irreversible reactions more common than reversible ones?

Kirsty Star 2H
Posts: 48
Joined: Fri Sep 28, 2018 12:24 am

### Re: irreversible and reversible

Yes, reversible reactions are actually just theoretical, since it would mean that all energy in the form of heat can be transferred to work, with nothing being lost to the surroundings, which is almost never possible. Lavelle said almost every reaction is irreversible, especially biological applications.

Heidi Ibarra Castillo 1D
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

### Re: irreversible and reversible

^ yes reversible reactions are generaly theorectical, majority will always be irreversible