Question

The amount of sulfur in aromatic monomers can be determined by differential pulse polarography. Standard solutions are prepared for analysis by dissolving 1.000 ml of the purified monomer in 25.00 ml of an electrolytic solvent, adding a known amount of S, deaerating, and measuring the peak current. The following results were obtained for a set of calibration standards.

ug of S added	peak current uA	ug of S added	peak current uA
0	0.14	112	2.41
28	0.70	168	3.42
56	1.23

Analysis of 1.000 mL sample, treated in the same manner as the standards, gives a peak current of 1.77 uA. Report the amount of sulfur present in the sample in mg/ml. SHOW WORK!!!!

Answer 1

From the table we can calculate the amount of sulpher present using peak current, this table is for standards by dissolving 1.0 ml of purified sample in 25 ml of an electrolytic solvent, in this standards amount of S is known, then we can calculate the unknown S present in solution from peak current. the 1.0 ml sample is treated in same manner as standard, we have to find the amount of sulpher in miligrams/ml.

ip = KCs,

ip = 1.77 µA = KCs × (25.00 mL / 26 mL) *(1 mL / 26 mL,

CONCENTRATION OF SULPHER= 0.06531 mg/ml

also we can calculate from table, for 28 ug of sulpher peak current is 0.70 uA, THEN BY CROSS MULTIPLYING,

28=0.70, ?=1.77, 28*1.77=49.56/0.70=70.8 ug of sulpher,

70.8/1000=0.0708 mg/ml