Question

Calculate the monolayer capacity and specific surface area of a sample of silica gel using BET theory. The sample was found to have a weight of 2.56 g and a total surface area of 260 m²/g. The gas used for adsorption was nitrogen at a temperature of 77 K and a pressure range of 0.01-0.3 P/P₀. The plot of (P/P₀)/(V₀/V) versus P/P₀ generated a straight line with a slope of 4.2×10⁻³.

Answer 1

To calculate the monolayer capacity and specific surface area of the silica gel sample using the BET theory, we need to use the BET equation: P/P / V/V  = 1/VmC +  C-1 /VmC *  P/P Where:P/P is the relative pressureV/V is the volume of gas adsorbedVm is the volume of gas adsorbed at monolayer capacityC is the BET constantWe are given the slope of the plot of  P/P / V/V  versus P/P, which is 4.210. This slope is equal to  C-1 /VmC. We can rearrange the equation to solve for Vm:Vm =  C-1 /slopeHowever, we don't have the value of C. To find C, we need to use the intercept of the plot. The intercept is equal to 1/VmC. We can rearrange the equation to solve for C:C = 1/ intercept * Vm Unfortunately, the intercept is not provided in the problem. Without the intercept, we cannot calculate the BET constant  C  and the monolayer capacity  Vm .If you can provide the intercept of the plot, we can proceed with the calculation.