Question

If n-dodecane (C12 alkane, straight chain) were a liquid impurity, would simple distillation be the technique used to isolate ethyl acetate? Explain.

If n-pentane (alkane, straight chain) were a liquid impurity, would simple distillation be the technique used to isolate ethyl acetate? Explain.

Answer 1

The boiling point of  n-dodecane (C12 alkane, straight chain) is 216 ^oC and ethyl acetate is 77 ^oC. Since, the difference between the bioling point of  n-dodecane and ethyl acetate is 216 ^oC - 77 ^oC = 139 ^oC, therefore, a simple distillation can be used to isolate ethyl acetate.

Now, The boiling point of n-pentane is 36 ^oC and ethyl acetate is 77 ^oC. The difference between the bioling point of ethyl acetate and n-pentane and is 77 ^oC - 36^oC = 41 ^oC. Although the difference is  41 ^oC but the simple disitllation can not be used, beacuse while carrying out the distillation of mixture of these two, the n-pentane distills along with ethyl acetate. We need to use fractional distillation to isolate ethyl acetate.