Question

Under certain circumstances, potassium ions ( K+K+ ) in a cell will move across the cell membrane from the inside to the outside. The potential inside the cell is −70.5 mV−70.5 mV and the potential outside the cell is zero. What is the change in the electrical potential energy of a single potassium ion as it moves across the membrane?

Answer 1

the change in the electrical potential energy of a single potassium ion as it moves across the membrane is 1.12941 × 10⁻²⁰ J

Step-by-step explanation:

The formula used in determining the change in the electrical potential energy can be expressed by the relation.

Charge in electrical Potential energy =
`q ( V_2 - V_1)`

where q = the potassium ion

q = 18 electrons and 19 protons

q = 19-18 = 1 electron

1 electron = 1.602 × 10⁻¹⁹ Coulombs

Thus;

the potential inside the cell is −70.5 mV

= -70.5 × 10⁻³ V

∴ Charge in electrical Potential energy =
`q ( V_2 - V_1)`

Charge in electrical Potential energy =
`1.602*10^(-19) ( 0 - (-70.5*10^(-3))`

Charge in electrical Potential energy = 1.12941 × 10⁻²⁰ J

Thus; the change in the electrical potential energy of a single potassium ion as it moves across the membrane is 1.12941 × 10⁻²⁰ J