Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Make your likes visible on Facebook?

Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.

No, thanks

Preparation and standardization of sodium thiosulfate

No description
by

generose carumba

on 5 March 2014

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of Preparation and standardization of sodium thiosulfate

Preparation and standardization of 0.1 N sodium thiosulfate
Materials
Procedure
Question and Answers
Sodium thiosulfate
CHARACTERISTICS:
monoclinic
USES:
antidote of cyanide poisoning
treatment of calciphylaxis in haemodialysis patients
Reagents
Dissolve sodium thiosulfate and sodium carbonate in 1000 mL of recently boiled and cooled water.
Weigh accurately the Potassium dichromate (
previously pulverized and dried at 120 C for 4 hours
) and dissolved in 1000 mL of water in a glass stoppered 500 mL flask.
Swirl to dissolve the sample, remove the stopper and add KI, Sodium bicarbonate and hydrochloric acid stopper the flask.
Swirl to mix, and allow to stand in dark for 10 minutes.
Rinse the stopper and the inner walls of the flask with water.
Titrate the liberated iodine with sodium thiosulfate until the solution is only faintly
yellow
in color.
Add the starch TS and continue the titration to the discharge of
blue
color.
Why should the water use in dissolving sodium thiosulfate is recently boiled?
FOR THE PURPOSE OF STERILIZATION
IT COMPELS CARBON DIOXIDE
What is the use of adding sodium carbonate to the sodium thiosulfate solution?
USE AS PRESERVATIVE TO PREVENT ACID-CATALYZED HYDROLYSIS
Write the chemical equation of sodium thiosulfate and potassium dichromate?
What is responsible for the greenish color of the solution at the endpoint of the titration?
POTASSIUM IODIDE
Aside from using potassium dichromate, how is sodium thiosulfate standardize?
SODIUM THIOSULFATE CAN BE STANDARDIZED AGAINST PURE IODINE DISSOLVED IN KI OR AGAINST IODINE SET FREE FROM AN ACIDIFIED SOLUTION OF KI BY STANDARD SOLUTION OF POTASSIUM PERMANGANATE OR VARIOUS PRIMARY STANDARD OXIDIZING AGENTS SUCH AS POTASSIUM IODATE.

26 g Sodium thiosulfate
200 mg Sodium carbonate
210 mg Potassium dichromate
5 mL hydrochloric acid
2 g Sodium bicarbonate
3 g Potassium iodide
Starch TS
REFERENCE:
Jenkin's Quantitative Pharmaceutical Chemistry by Digangi and Knevel
Analytical balance
Beaker
Stoppered flask
Buret
watch glass
Pipette/aspirator
Wash bottle
SUMMARY
Primary standard:
potassium dichromate
Standard solution
: sodium thiosulfate
Indicator:
starch TS
Endpoint:
blue color
Method:
Iodimetry method
K2Cr2O7 + 6KI +14HCl 3I2 + 2CrCl3 +8KCl +7H2O
Full transcript