# The analysis of pesticides for environmental extracts using chromatography typically requires a solvent exchange from dichloromethane (DCM) to a chromatograph-compatible solvent such as hexane. If DCM and hexane can be separated after the procedure, they can be recycled to reduce waste. A mixture of liquid hexane and DCM (50wt% hexane) is fed to an evaporator resulting in a vapor containing 70wt% hexane and liquid containing 10wt% hexane.a. Draw and label a flowchart for a continuous and steady-state process with a feed rate of 200.0 kg/min. Write out the general mass balance equations for total mass and hexane. Explain why you are discarding any of the terms. Solve the equations to find the mass flow rates of the vapor and liquid streams leaving the evaporator.b. Draw and label a flowchart if the process is performed in a closed container filled initially with 200.0 kg of the 50:50 mixture. Write out the integral mass balances for total mass and hexane. Explain why you are discarding any of the terms. Solve the equations to find the masses of the final vapor and liquid phases.

The analysis of pesticides for environmental extracts using chromatography typically requires a solvent exchange from dichloromethane (DCM) to a chromatograph-compatible solvent such as hexane. If DCM and hexane can be separated after the procedure, they can be recycled to reduce waste. A mixture of liquid hexane and DCM (50wt% hexane) is fed to an evaporator resulting in a vapor containing 70wt% hexane and liquid containing 10wt% hexane.

a. Draw and label a flowchart for a continuous and steady-state process with a feed rate of 200.0 kg/min. Write out the general mass balance equations for total mass and hexane. Explain why you are discarding any of the terms. Solve the equations to find the mass flow rates of the vapor and liquid streams leaving the evaporator.

b. Draw and label a flowchart if the process is performed in a closed container filled initially with 200.0 kg of the 50:50 mixture. Write out the integral mass balances for total mass and hexane. Explain why you are discarding any of the terms. Solve the equations to find the masses of the final vapor and liquid phases.

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