What is the volume of fluid that must flow through the semipermeable membrane?

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SUMMARY

The discussion centers on calculating the volume of fluid flowing through a semipermeable membrane under specific conditions. The participant initially calculated that a current of 1 µA corresponds to a transport rate of 0.1 µL of solution per second, based on an osmolarity of 1000 mOsm/L. However, they later identified an error in their conversion of Coulombs to moles, specifically regarding Faraday's constant, which led to discrepancies in their calculations when using a current of 100 µA and an osmolarity of 300 mOsm/L.

PREREQUISITES
  • Understanding of osmolarity and its implications in fluid transport
  • Knowledge of Faraday's constant and its application in electrochemistry
  • Familiarity with the principles of ion flow and current measurement
  • Basic concepts of semipermeable membranes and their functions
NEXT STEPS
  • Study the application of Faraday's constant in electrochemical calculations
  • Learn about the principles of osmotic pressure and its effects on fluid movement
  • Explore the dynamics of ion transport across semipermeable membranes
  • Investigate methods for measuring current and ion flow in biological systems
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Researchers in biophysics, biochemistry, and anyone involved in the study of membrane transport mechanisms will benefit from this discussion.

Andy Resnick
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I think this is a simple problem to solve, but I keep getting nonsense answers.

The question: two reserviors held at constant osmolarity (say 1000 mOsm/l) are connected by a semipermeable membrane. A current of 1 uA is measured across the membrane. What is the volume of fluid that must flow through the membrane?

So I have 1 uA = 1 umol/s ion flow, and 1000 mOsm/l means that 1 umol of osmolyte corresponds to 10^-7 liters of solution. So, 0.1 ul of solution is transported per second. Is this correct?

The reason I think I'm having trouble is that using my actual numbers (100 uA, 300 mOsm/l) I get very high fluid transport rates. Much higher than what is observed.
 
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Never mind- I found the error. It was in converting Coulombs to moles- I was not using the correct conversion (Faraday's constant).

1 uA corresponds to 1.04 *10^-5 umol/s of charge flux, in case anyone is interested.
 

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