The problem asks which parameters in the Nernst-Planck equation govern chloride migration. The options are: A. Concentration gradient B. Binding isotherm C. Electrical potential D. Convection velocity E. Temperature

1. Problem Description

The problem asks which parameters in the Nernst-Planck equation govern chloride migration. The options are:

A. Concentration gradient

B. Binding isotherm

C. Electrical potential

D. Convection velocity

E. Temperature

2. Solution Steps

The Nernst-Planck equation describes the flux of ions under the influence of a concentration gradient and an electric field. The equation combines Fick's first law of diffusion with the Poisson equation. The equation is:

$J_i = -D_i \nabla c_i - z_i u_i F c_i \nabla \phi + c_i v$

where:

$J_i$ is the flux of ion $i$

$D_i$ is the diffusion coefficient of ion $i$

$\nabla c_i$ is the concentration gradient of ion $i$

$z_i$ is the valence of ion $i$

$u_i$ is the mobility of ion $i$

$F$ is Faraday's constant

$c_i$ is the concentration of ion $i$

$\nabla \phi$ is the electric potential gradient

$v$ is the convection velocity

From the equation, we can see that the following parameters govern the chloride migration:

- Concentration gradient ($\nabla c_i$)

- Electrical potential ($\nabla \phi$)

- Convection velocity ($v$)

- Diffusion coefficient ($D_i$), which depends on temperature. Therefore, temperature also has an effect.

A. Concentration gradient: This is directly in the equation.

B. Binding isotherm: This is not directly in the Nernst-Planck equation.

C. Electrical potential: This is directly in the equation.

D. Convection velocity: This is directly in the equation.

E. Temperature: Temperature affects the diffusion coefficient, and thus affects ion migration.

The most direct and relevant parameters are concentration gradient and electrical potential. Convection velocity also directly contributes, but is less common. Temperature is also important, since temperature influences ionic mobility.

3. Final Answer

A. Concentration gradient

C. Electrical potential

D. Convection velocity

E. Temperature