To determine the diffusion time for a molecule, the distance to be traveled and the diffusion coefficient are required. With these, the time can be calculated using the formula t = (Xrms)^2 / (2D), where Xrms is the distance and D is the diffusion coefficient.
To calculate the time it takes for a molecule with a diffusion coefficient of 3x10-7 cm2 s-1 to diffuse across a cell, you can use the formula for average distance traveled (Xrms) by diffusion:
Xrms = √(2D*t)
By rearranging this equation to solve for time (t), we get:
t = (Xrms)2 / (2D)
However, to provide a concrete answer, the precise distance that the molecule needs to travel must be known. Without this information, an exact time cannot be determined. Remember that the diffusion process is affected by factors such as molecular mass, as more massive molecules diffuse more slowly, and temperature, since higher temperatures increase molecular speeds and thus the diffusion constant.