Moles Of H2S

Question 1

Purpose

Answer 1

Determine apparent hydrogen sulfide in anime solutions. Hydrogen sulfide is determined by oxidation with standard iodine solution in acid medium. Thiosulfate is also titrated and is included as apparent H2S in calculation

Question 2

Procedure for Blanks

Answer 2

A blank should be run with every batch of samples and when new iodine or sodium thiosulfate is used.

• in 250mL Erlenmeyer flask add following in order listed: 50mL DI water, 25mL of 0.1 N iodine, 5mL of concentrated Hydrochloric acid
• add 3-5 drops starch indicator and gently mix
• Titrate sample with 0.1 N sodium thiosulfate until milky white or clear (starch indicator may be used to verify titration complete)
• number of milliliter a used to Titrate milky white color is recorded as blank

Question 3

Procedure for Samples

Answer 3

• in 250mL Erlenmeyer flask add following in order listed: 50mL DI water, 25mL 0.1 N iodine, 5mL of concentrated Hydrochloric acid
• place flask in scale and tare
• add 1mL of amine sample and record weight
• add 3-5 drops Starch indicator and gently mix (if mixture turns white, more iodine will have to be added, make sure to record the extra iodine and add to blank iodine number for that specific sample)
• Titrate sample with 0.1N sodium thiosulfate until milky white or clear

Question 4

Calculations

Answer 4

This calculation cannot be performed until Wt% MDEA has been established
•calculation for moles H2S performed in LIMS after all raw data entered
•to calculate manually refer to method or sheet in titration lab
•after calculation report results as molesH2S/Mole MDEA