Based on the solubility test results, indicate for each compound if there is a s

Question

Based on the solubility test results, indicate for each compound if there is a suitable solvent for a single-solvent recrystallization and if there are two solvents suitable for a two-solvent recrystallization (briefly explain your reasoning in each case).

[3]

compound

water

ethanol

ethyl acetate

cold

25 0C

hot

cold

25 0C

hot

cold

25 0C

hot

acetanilide

-

I

PS

S

PS

S

-

S

S

sucrose

S

S

-

-

PS

PS

-

I

I

naphthalene

-

I

I

-

I

S

S

PS

-

compound

water

ethanol

ethyl acetate

cold

25 0C

hot

cold

25 0C

hot

cold

25 0C

hot

acetanilide

-

I

PS

S

PS

S

-

S

S

sucrose

S

S

-

-

PS

PS

-

I

I

naphthalene

-

I

I

-

I

S

S

PS

-

Explanation / Answer

According to literature, a single-solvent recrystallization occurs in presence of a solvent that can dissolve solute at hot temperature and has low solubility of this at cold temperature.

A two-solvent recrystallization will performed if there is no solvent that matches the previous characteristics because it has partial solubility of solute at cold temperature, that is why we use a second solvent that needs to be mixable with the first one, but in addition it needs to have poorly solubility of solute at cold temperature.

Said that:

For Acetanilide: There is no solvent suitable for a single-solvent recrystallization, because there is no appreciable change of solubility with temperature for any of the three. But we can use the par water/ethanol as suitable two-solvent recrystallization, with ethanol first (dissolve it well but no good recovery) and water secondly (dissolves it partially when hot)

For Sucrose: There is no solvent suitable for a single-solvent recrystallization, because there is no change of solubility with temperature for any of the three. And no par can be used for two-solvent recrystallization for the same reason.

For Naphthalene: Only ethanol is suitable for a single-solvent recrystallization, because it dissolves it when hot and does not when cold. No need a two-solvent recrystallization.

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.