Question

1. In this distillation experiment we start the experiment with 10 mL of liquid mixture ofcyclohexane and toluene. However, it is not possible to obtain all 10 mL back under thecurrent procedure particularly for fractional distillation. Explain why that is the case for distillation and in particular for fractional distillation.

2. How could you modify the experiment and collect all 10 mL of the startingmaterials.

3. Plot a theoretical distillation curve of temperature (y-axis) vs. volume in mL (x-axis) fora 15 mL of a mixture containing 60% 1-propanol and 40% 2-propanol. Are these twocompounds easier to separate by distillation than cyclohexane and toluene? Explain youranswer.

4. In this experiment you were asked to collect two fractions and early fraction and a latefraction. Which of the two fractions would be richer in cyclohexane? Would there be adifference between the percent of cyclohexane in the fractions collected from fractionalvs. simple distillation.

5. What method of purification would you use to purify methanol from a solution ofmethanol and NaCl? Be specific and explain your choice of method.

Answer 1

!) fractional distillation works on the basis of roults law. it means collection of volume depends upon its molefraction and boiling pont. In the process of distilation some fractions are lost in the form of vapors i.e evoporation.

2) To arrest the process of loss of material, provide with more no. of therotical plates in distillatiion column.

3) No the compounds o 1-propanol posses 97⁰C and 2- propanol is 82⁰C i.e posses minimum boiling point . so, they cannot seperate easily

4) In general Cyclohexane have 81⁰C i.e low boilin point . so it collected as first fraction.

Simple distillation is a crude method, cannot seperate easily but in fractional distillation mixture was allowed to different plates in column and mixture eaily resolved.

5) NaCl dissolved in methanol and it seperated by fractional distillation method where Nacl is an impurity as well as it increase boiling point of methanol.