12.1 Solubility-Base Methods

Question 1

“like dissolves like” meaning

Answer 1

polar substances will associate with other polar substances

nonpolar substances will associate with other nonpolar substances

Question 2

extraction

Answer 2

the transfer of a dissolved compound (the desired product) from a starting solvent into a solvent in which the product is more soluble

based on the concept “like dissolves like”

leaves most impurities behind in the first/original solvent

Question 3

“immiscible” meaning

Answer 3

that the two solvents form two layers that do not mix (ex. water and oil)

Question 4

aqueous phase/layer

Answer 4

consists of polar water

Question 5

organic phase/layer

Answer 5

the nonpolar phase

Question 6

what equipment is used to separate the aqueous and organic phases of a separated mixture?

Answer 6

separatory funnel

Question 7

which layer will be on top/bottom once separated?

Answer 7

while it is more common for the aqueous layer to be on top, the opposite can occur as it depends on their relative densities

the MORE DENSE layer will be on the bottom, the LESS DENSE layer will be on top

Question 8

effective extractions involve ______ rather than ______

Answer 8

effective extractions involve multiple extraction with fresh water rather than a single extraction with a larger volume of water

Question 9

how is the product obtained once it has been isolated in solvent

Answer 9

the solvent is evaporated, usually by using a rotary evaporator

Question 10

what device is used to evaporate the solvent off of the product?

Answer 10

rotary evaporator (rotovap)

Question 11

washing

Answer 11

the reverse of extraction; removes unwanted impurities into a second solvent

the desired compound stays in its current layer

Question 12

extraction vs washing

Answer 12

extraction pulls the desired product into a new phase, leaving impurities in the original solvent

washing pulls impurities into a new phase and leaves the desired product in the original solvent

Question 13

filtration

Answer 13

a process used to separate solids from liquids using a filter (ex. paper) that allows the fluid to pass through but not the solid

Question 14

what is the solid phase of filtration called?

Answer 14

the residue

Question 15

what is the liquid phase of filtration called?

Answer 15

the filtrate

Question 16

gravity filtration

Answer 16

the solvents own weight puts it through the filter

more commonly used when the product of interest is in the filtrate

hot solvent is generally used to keep the product dissolved in liquid

Question 17

vacuum filtration

Answer 17

the solvent is forced through the filter by a vacuum connected to the flask

more often used when the solid is the desired product

Question 18

recrystallization

Answer 18

a method for further purifying crystals in solution

first we dissolve our product in a minimum amount of hot solvent and let it recrystallized as it cools

(ideally the impurities remain in the solvent and only the product crystallizes are room temperature)

the crystal is then isolated via vacuum filtration

Question 19

what type of solvent should be closed for recrystallization? why?

Answer 19

the product is readily soluble at high temperatures but insoluble at room temperature

(so when the solution cools, only the desired product will recrystallize out of solution, excluding impurities)