Question

Part D: extraction of the mandelic acid solution with one 50ml aliquot of organic solvent

a) Calculate the moles of sodium hydroxide used to titrate the 5.0ml of extracted water

b) calculate the moles of mandelic acid in the 5.0ml of extracted water

c) determine the mass of the mandelic acid in the 5.0ml of extracted water.

d) determine the concentration of mandelic acid in g/ml

Part E:

Rank the extraction techniques from best to poorest in their ability to extract the mandelic acid from water.

hint: see parts a-c in separately asked questions

Determination of a partition coefficient

Mass of mandelic acid: 6.01g

[NaOH]: 0.1036

Table 1: titration of a 10.0 ml aliquot of mandelic acid solution with standard NaOH

burette reading	trial 1	trial 2	trial 3
final reading	38.1ml	41.40ml	41.02ml
initial reading	0.0	2.80	2.78
volume NaOH used	38.1ml	38.60ml	38.24ml

average of three titrations: 38.31ml

table 2: titration of the 5.0 ml sample of extracted water

burette reading	Part B: extraction with one 25ml aliquot of ether	Part C: extraction with two 25ml aliquots of ether	Part D: extration with one 50ml aliquot of ether
final reading	4.20	5.20	7.5
initial reading	1.05	4.50	5.4
volume NaOH used	3.15	0.70	2.1

Answer 1