Question

Under certain circumstances, potassium ions (K ) in a cell will move across the 8.15 nm thick cell membrane from the inside to the outside. The potential inside the cell is -80.5 mV and the potential outside is zero. What is the change in the electrical potential energy of a single potassium ion as it moves across the membrane?Does the potential energy of the potassium ions increase, decrease, or remain the same as the ions move from the inside to the outside?

Answer 1

Answer:

$1.288\times 10^{-20}\ J$

Increase

Explanation:

q = Charge in the potassium ion = $19e-18e$

e = Charge of electron = $1.6\times 10^{-19}\ C$

$V_2-V_1$ = Change in potential = $0-(-80.5\times 10^{-3})$

Change in electric potential is given by

$E=q(V_2-V_1)\\\Rightarrow E=(19e-18e)(0-(-80.5\times 10^{-3})\\\Rightarrow E=1.6\times 10^{-19}\times 80.5\times 10^{-3}\\\Rightarrow E=1.288\times 10^{-20}\ J$

The energy is $1.288\times 10^{-20}\ J$

The potential energy will increase.