Question

Each of the solvents listed below are used in experiments in this text to extract organic compounds from aqueous solutions.

(i)Methylene chloride

(ii)pentane

(iii)Toluene

(iv)Diethyl ether

Will the organic phase be the upper or lower layer when each of these solvents is mixed with water? Explain your an- swer for each case. (b) If you placed an ice cube in each of the solvents i–iv listed above in (a), would you expect an ice cube placed in each to float? Explain your answer for each case

Answer 1

So, first we have to look up the densities of each solvent and water

Densities at 20°C:

Density H₂O =0.998 g /mL

Density CH₂Cl₂=1.327 g /mL

Density C₅H₁₂= 0.63 g/mL

Density Toluene = 0.87 g/mL

Density diethyl ether= 0.713 g/mL

So, all the solvents that possess density lower than the water will be in the upper layer. These are

(ii) pentane

(iii)Toluene

(iv)Diethyl ether

In common words the solvents with less density than water floats over the water.

By contrast the Methylene chloride with a higher density than water will go to the bottom layer.

As a general rule, most

b) At 0°C the density of ice is around 0.9167g/mL. Under the same approach we did in a) and supposing no change in the densities of the organic solvents listed, the ice will float only in methylene chloride. The other solvents have a lower density than ice, then the ICE would sink in them.

If you have any doubts please comment this :)