CHEN 231 Eall 3o15 Assign mnct 4A A liquid mixture of benzene and toluene contai

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CHEN 231 Eall 3o15 Assign mnct 4A 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 liqud containing 10.6% benzene by mass (a) Suppose the rocess s to be carried out contimuously and at steady state,with a feed rate of 1000 kg/h of the 55% mixture. Let mulkgh) and nr(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 m, and m. For each bal- ance, state which terms of the general balance equation (accumulation input generation- output- consumption) you discarded and why you discarded them (Sce Example 42-2.)-X (b) Next, suppose the process is to be carried out in a closed container that initially contains 1000kg of the liquid mixture. Let m(kg) and m(kg) be the masses of the finai vapor and liquid phases respectively Draw and label a process howchart, then write and solve integral balances on total mass and on benzene to determine m and m. For each balance, state which terms of the general balance equation (accunulation- input+ generation - output-consonption) 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 composations 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 contan 7% benzene instead of 10.6% One possable explanation is that a mistake was made in the measurement. Give at least five others. [Thinlk about assumptions you made in obtaining the solution of part (a)] K Exomple 4.2-2 Example 4.2-2 is olso in the Chapter 4A nafes,rage S akso in the

Explanation / Answer

According to the info, and the question you actually have, you want to know if your flow chart is right.

Well, you drew the flow chart good, but remember something. Like in part a) state: Accumulation = input + generation - output + consumption.

First you need to know what's the input and generation.

The input would be the 100 kg/hr, and it tells you that 55% it's from benzene, so, logically, 55 kg/hr belongs to benzene and 45 kg/h to toluene. That part is good as you put it.

The next part, the generation is what goes out of the reactor or distillator or anything else. In this case, it says that you want to partially evaporate the mixture, containing 85% benzene. So if initially you have 100 kg/hr, and that mixture is 55 kg/hr, then the 85% would be:

55 kg/h x 0.85 = 46.75 kg/h of benzene and from toluene:

45 kg/h x 0.15 = 6.75 kg/h of toluene.

So that's the value of generation of benzene.

Now in the residual, would be the ml (mass of liquid) divided into this:

55 kg x 0.106 = 5.83 kg/hr

45 x 0.894 = 40.23 kg/h

So in the part of generation in output, correct the following:

85% benzene

mg = 46.75 kg/h of benzene

and the residual:

10.6% benzene

ml = 5.83 kg/hr of benzene

You can put the mass of toluen too. If you need something else you can tell me in a comment and I'll gladly help you with that. If you need help with the other parts you can tell me too, but you may try to put it into another question.

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