Transcript Extraction - Salem High School

Extraction
Extraction is a general theory for the recovery of a
substance from a mixture by bringing it into contact with a
solvent which preferentially dissolves the desired material.
In organic chemistry, the reaction product is frequently
obtained as a solution in water along with other organic and
inorganic byproducts.
Let’s get started
• To begin this lesson, click on the web address
below and view this first 12 pages.
• http://www.slideshare.net/Atharsaeedi/extrac
tion-theory
• Return to this powerpoint after viewing the
first 12 pages.
Let’s do the math
By definition, the distribution coefficient is:
KD =
concentration in the organic layer
concentration in the water layer
Let us consider compound A:
10g of compound A will dissolve in 100ml ethyl ether (an organic compound)
2g of compound A will dissolve in 100ml of water
Calculate the KD for compound A
Determining the KD
KD =
concentration in the organic layer = 10g/100ml
concentration in the water layer
2g/100ml
KD= 5
If you are given a solution of 1g of compound A dissolved in 100ml of water, how
much could you extract if you did three extractions using 25ml of ethyl ether with
each extraction?
Set up the problem
Solve for X by cross multiplying two times. Go to the next page to
see the value for X.
X = 0.556g
• This means that 0.556g of compound A has
now moved to the ethyl ether layer.
• How much compound A remains in the water?
• 1g – 0.556g = 0.444g of compound A in the
water.
• Now set up the problem for the next
extraction:
2nd Extraction
Cross multiply twice and solve for X.
X=0.247g
• This means that 0.247 more grams of
compound A have moved from the water layer
to the ethyl ether.
• How much compound A remains in the water?
• 0.444g-0.247g = 0.197g of compound A are
still in the water.
• Set up the problem for the third extraction.
3rd Extraction
Solve for X and you should obtain X = 0.109g of compound A.
What is the total amount of compound A extracted?
0.556g + 0.247g + 0.109g = 0.912g extracted in the ethyl ether.
1g – 0.912g = 0.88g of compound A remaining in the water.
Try another problem?
• 15g of compound J dissolves in 100ml of
benzene.
• 5g of compound J dissolves in water.
• You are given a solution with 2g of compound
J dissolved in 100ml of water. If you do two
extractions with 50ml of benzene in each
extraction, how many grams of compound A
can you extract from the water?
Solve for KD and 1st extraction
2nd extraction and final answer