Final answer:
The equilibrium potential for an ion across a cell membrane can be determined using the Nernst equation, which accounts for ion concentration, charge, and temperature to calculate the cell potential.
Step-by-step explanation:
To get a numerical value for the equilibrium potential when we know the concentrations of an ion inside and outside a cell, we use the Nernst equation. This equation takes into account the concentrations of the ions, the charge on the ions (n), temperature (usually at 25°C or 298 K), and the standard cell potential (E°cell). Specifically, the Nernst equation, which at 298 K is often simplified to Ecell = E°cell - (0.0591/n) log Q, where Q is the reaction quotient, allows us to calculate Ecell. When n, the number of electrons transferred, is 2 for the cell reaction given, the cell potential changes by approximately 0.0591 V for each ten-fold change in the concentration ratio of the ions.
In the context of biochemistry or neurology, determining the equilibrium potential is crucial for understanding how ions move across cell membranes, which is integral to the function of neurons and muscle cells. In such cases, ions typically enter cells through protein channels or pumps embedded in the cell membrane, and the flow of these ions affects the voltage across the membrane, which is critical for the propagation of nerve impulses or muscle contraction.