Molasses Sulphur dioxide determination
1. Iodine solution: Dissolve 12 gms of Potassium Iodide (KI) in 9 mls of water, add 8 gms of Iodine crystals,
stir until completely in solution and dilute to 200 ml. Store the solution in glass stoppered amber reagent
bottle. Dilute 12.8 ml of the above iodine solution with water to 200 mls to make 0.02 N Iodine solution.
2.
9 N H2S04
Add 50 mls of conc. Sulphuric acid (96-98 % w/w) to 150 ml of water cooled in an ice bath. Mix well.
3.
10 % NaOH
Dissolve slightly more than 20 gms of NaOH in recently boiled and cooled water and dilute to 200 ml.
in a plastic bottle.
Store
PROCEDURE
Weigh 25 gms of molasses into each of two 250 mls conical flasks. Add about 50 mls of hot water and stir
until homogenous solution is obtained. Add two ice cubes and place the conical flasks and contents in a
0
0
water bath near 0 C, when the solution reaches 5 C, add 10 mls of NaOH AND allow the conical flasks to
remain in water bath for additional 10 minutes. The add 10 ml of 9NH 2SO4 and 2 ml of starch indicator to
both beakers and mix. Immediately titrate one of t he conical flasks with 0.02 N Iodine solution until the blue
colour purists for 1 minute. A blank is obtained by adding 10 ml of 3 % H 202 to the other conical flask before
titrating.
Calculation
SO2 ( PPM ) 
( SampleTitreValue  BlankTitreValue) x 0.02 x0.032 x 10000000
Sampleweight