Question

a) A mixture of solid sucrose and naphthalene was mixed with hexane. Some of the solid dissolved, but some solid remained in the mixture. Which component of the mixture is likely to be the solid?

b) If you needed to separate the sucrose and naphthalene in your original mixture, how might you accomplish the separation and recover both solids?

Answer 1

a)

solid sucrose

solid naphthalene

hexane --> nonpolar

note that sucrose is slightly polar; naphthalene is nonpolar

recall that like dissolves like

so hexane + naphthalene are likely to form solution

sucrose is likely to be slightly soluble

so some sucrose is epxected to form solid

b)

Add water to the mix; shake so:

sucrose goes from nonpolar solution to aqueous solution

naphthalene remains in the nonpolar solvnet ( hexane )

remove water; vaporize, there will be sucrose crystals

Repeat until most sucrose is recovered