a The potential on the outer surface of the membrane is 648

(a) The potential on the outer surface of the membrane is +64.8 mV greater than that on the inside surface. How much charge resides on the outer surface?
__________C

(b) If the charge in part (a) is due to K⁺ ions (charge +e), how many such ions are present on the outer surface?
__________ions

Solution

c = k epsilon₀ A / d

= (5.40 * 8.85 * 10^-12 * 5.30 * 10^-9) / (9.10 * 10^-9)

= 2.78 * 10^-11 F

a) q = C V = 2.78 * 10^-11 * 64.8 * 10^-3

q = 1.80 * 10^-12 C

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b) Number of ions = ( 1.80 * 10^-12 ) / ( 1.6 * 10-19 )

= 1.13 * 10⁷