A liquid mixture of benzene and toluene contains 55.0% benzene by mass. The mixture is to be partially evaporated to yield a vapor containing 85.0% benzene and a residual liquid containing 10.6% benzene by mass.

(a) Suppose the process is to be carried out continuously and at steady state, with a feed rate of 100.0 kg/h of the 55% mixture. Let mv (kg/h) and m1 (kg/h) be the mass flow rates of the vapor and liquid product streams, respectively. Draw and label a process flowchart, then write and solve balances on total mass and on benzene to determine the expected values of mv and m1. For each balance, state which terms of the general balance equation (accumulation = input + generation – output – consumption) you discarded and why you discarded them.

(b) Next, suppose the process is to be carried out in a closed container that initially contains 100.0 kg of the liquid mixture. Let mv (kg) and m1 (kg) be the masses of the final vapor and liquid phases respectively. Draw and label a process flowchart, then write and solve integral balances on total mass and on benzene to determine mv and m1. For each balance, state which terms of the general balance equation (accumulation = input + generation – output – consumption) you discarded and why you discarded them.

(c) Returning to the continuous process, suppose the evaporator is built and started up and the product stream flow rates and compositions are measured. The measured percentage of benzene in the vapor stream is 85% and the product stream flow rates have the values calculated in part (a), but the liquid product stream is found to contain 7%benzcne instead of 10.6%. One possible explanation is that a mistake was made in the measurement. Give at least five others. [Think about assumptions you made in obtaining the solution of part (a).]