where \(A\) is the area of the supply face; \(D_{\text{H}_{2}}\) is the diffusion coefficient of \(\text{H}_{2}\)\(\Delta x\) is the distance between the top and bottom faces of the culture; and where \(\Delta C_{\text{H}_{2}}\) is the \(\text{H}_{2}\) concentration difference between the top and bottom faces of the culture. Assuming that the \(\text{H}_{2}\) concentration drops to zero by the bottom of the culture,