Question

Compound A has a solubility of 0.2 g/mL in toluene at toluene's boiling point and a solubility of 0.05 g/mL at 0 ºC. How much toluene would be necessary to recrystallize 3.2 g of A. What would be the maximum amount of A that could be recovered if the saturated solution was allowed to cool to 0 ºC. How much A would be recovered, if you accidentally used twice as much toluene as was necessary?

Answer 1

1) 16 mL of toluene is necessary to recrystallize 3.2 g of compound A

2) 2.4 g of A is the maximum amount that could be recovered.

3) 1.6 g of compound A can be recovered if you accidentally use twice as much toluene as was necessary

Step-by-step explanation:

1)

The volume of the solvent ( toluene) =
`(starting \ amount )/(solubility \ at \boiling \ point )`

=
`(3.2 \ g)/(0.2 \ g/mL)`

= 16 mL

∴ 16 mL of toluene is necessary to recrystallize 3.2 g of compound A

2)

The maximum amount A that could be recovered if the saturated solution was allowed to cool to 0 ºC is determined by the difference of the starting amount and amount left in the solution at 0 ºC

i.e

maximum amount of A = 3.2 - ( 16 mL × 0.05 g/mL)

= 3.2 g - 0.8 g

= 2.4 g

∴ 2.4 g of A is the maximum amount that could be recovered.

3)

Amount of A that would be recovered, if you accidentally used twice as much toluene as was necessary is calculated as follows;

amount of A = 3.2g - (32 mL × 0.05 g/mL)

= 3.2 g - 1.6 g

= 1.6 g

Thus; 1.6 g of compound A can be recovered if you accidentally use twice as much toluene as was necessary