Principle

The separation power of a rectification (fractionating) column can be determined using an appropriate binary mixture whose equilibrium composition is measured in the distillation flask and in the domed glass head of the distillation apparatus. The number of theoretical trays can be numerically or graphically obtained from the measured values.

Benefits

• Complete insight into all running processes, because all components have an evacuated, but not silvered isolating-coat
• Simple withdrawel of samples through 2 column intermediate pieces
• High separation efficiency through 2 large packed columns
• Secure, because the high-efficiency condensor of the column head also condense high-volatile liquids
• Simple adjustment of the reflux ratios through onehand-controlled column head

Tasks

1. Prepare 10 mixtures of methyl cyclohexane and n-heptane with substance ratios (mole fractions) from 0 to 1 and with step width of approximately 0.1. To record a calibration curve, determine the refractive indices of the mixtures and plot them against the mole fractions.
2. Distill a mixture of methyl cyclohexane and n-heptane in a rectification column with total reflux until an equilibrium has been established. Determine the composition of the condensate and the number of theoretical trays in the column for a throughput of 500 and 1000 ml/h.

Learning objectives

• Bubble tray column
• Rectification
• Raoult's law
• Henry's / Dalton's law
• Boiling-point diagram
• Reflux ratio

Necessary accessories

• Precision balance 620g/0.001g