a) In Escherichia Coli , coupled oxidation-reduction reactions within the cell m

Question

a) In Escherichia Coli, coupled oxidation-reduction reactions within the cell membrane have the effect of reducing the H+ concentration such that [H+]in/[H+]out­ is 0.4 and at the same time these reaction also create a membrane potential Vin - Voutof -0.120 V. Calculate the total G of the Gibbs free energy made available at T = 298 K by the transfer of 1 mol of protons from the outside to the inside of the cell as a result of encountering both the membrane potential and the concentration difference

b)The solute concentration in red blood cells (erythrocytes) gives rise to an osmotic pressure (relative to that of pure water) of 5.6 atm at 310 K. Would these cells shrink, swell, or remain unaffected in a solution at 310 K containing 12.5 g of the strong electrolyte Na2SO4 (MW = 142 g/mol) per liter of water? Please support your answer by means of a suitable calculation.

Explanation / Answer

a) delta G = -n*F*E = -1*96500*(-0.12) = 11580 J/mole = 11.580 kJ/mole

here n = moles of electron transfer taking place ; F = Faraday's constant = 96500 Columbs

b) Moles of Na2SO4 in 12.5 g of it = mass/molar mass = 12.5/142 = 0.088

Molar concenetration of the solution = moles of Na2SO4/volume of solution in litres = 0.088/1 = 0.088 M

Thus, Osmotic pressure of the Na2SO4 solution = C*R*T = 0.088*0.0821*310 = 2.24 atm

now, the osmotic pressure of solution is lower than that of the blood cells, it is a hypotonic solution.

Hence, the solution will swell.

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