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Topic: equilibrium reaction and osmotic pressure  (Read 3956 times)

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Offline billybob54

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equilibrium reaction and osmotic pressure
« on: February 17, 2009, 09:59:27 PM »
Suppose there was an equilibrium reaction A <-> B + C.  Also, we have a semi-permeable membrane that allows B and C to pass through, but not A.  We know that there is a certain amount of pressure required to separate B and C from A through this membrane.  This pressure is called the osmotic pressure.  Also, B and C release a certain amount of energy when they react.  We will call this amount of energy E.  I have a few questions about this.

1.  Is the osmotic pressure at all related to the Energy released by B + C when they react? If so why/how?
2.  If they are not related, is it possible that the Energy released by B + C reacting is greater than the energy required to create the osmotic pressure to force said B + C through the membrane to separate them from A?

If 2 is possible I have more questions to follow.

Offline Yggdrasil

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Re: equilibrium reaction and osmotic pressure
« Reply #1 on: February 17, 2009, 11:18:11 PM »
Suppose there was an equilibrium reaction A <-> B + C.  Also, we have a semi-permeable membrane that allows B and C to pass through, but not A.  We know that there is a certain amount of pressure required to separate B and C from A through this membrane.  This pressure is called the osmotic pressure.  Also, B and C release a certain amount of energy when they react.  We will call this amount of energy E.  I have a few questions about this.

1.  Is the osmotic pressure at all related to the Energy released by B + C when they react? If so why/how?

The osmotic pressure and the energy required to transport B and C across the membrane is solely related to the concentrations of B and C on either side of the membrane.  (assuming B and C are uncharged.  Things become more complicated if you have to take charge into account).

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2.  If they are not related, is it possible that the Energy released by B + C reacting is greater than the energy required to create the osmotic pressure to force said B + C through the membrane to separate them from A?

Sure.  If the concentrations of B and C are equal on both sides of the membrane, no energy is required to transport the molecules across the barrier.  Of course, the energy released by a reaction is primarily heat which is hard to harness in order to perform work.

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