Question

A Na+ ion moves from inside a cell, where the electric potential is -70 mV , to outside the cell, where the potential is 0 V. What is the change in the ion's electric potential energy as it moves from inside to outside the cell? The answer is in eV.

Answer 1

The change in electric potential energy for a Na+ ion moving from inside a cell with an electric potential of -70 mV to outside where the potential is 0 V is 0.07 eV.

Step-by-step explanation:

The question involves calculating the change in the electric potential energy of a Na+ ion as it moves from inside a cell, where the electric potential is -70 mV, to outside the cell, where the potential is 0 V. We know that the electric potential energy (EPE) of a charged particle is given by EPE = qV, where 'q' is the charge of the ion and 'V' is the electric potential. Since the charge of a Na+ ion is approximately +1 elementary charge (e) and the change in electric potential (ΔV) is 70 mV or 0.07 V, we can calculate this in electron volts (eV) which is an energy unit where 1 eV is the energy gained by the charge of a single electron moved across an electric potential of 1 volt.

So the change in electric potential energy will be equal to the charge of the ion multiplied by the change in potential (0 V - (-0.07 V)), which is +1e * 0.07 V = 0.07 eV. Hence, as the Na+ ion moves from inside to outside the cell, the change in the ion's electric potential energy is 0.07 eV.