What Sizes do we Supply Iodine Indicator in?
- We supply iodine indicator in 100g containers
- Discounts available for bulk orders over 4 items
- We also offer iodine 0.05M and 0.005M solutions
We offer many other options with all of our products, from customised labelling to specific pack sizes. We also offer free technical advice to all our customers. Just contact a member of our sales team and we’ll be happy to help you.
How Can Iodine be Used as an Indicator?
This element is extremely useful in analytical chemistry to identify the presence of alkenes and starch, as well as oxidising and reducing compounds. Colour changes in these reactions are ideal to spot their presence in many analytical methods.
For example, the presence and concentration of an oxidising agent can be determined by adding excess iodide. This oxidation causes the break of the triiodide bond, converting iodide (I3) to iodine (3I-) and giving the solution a dark brown colour. This solution is then titrated with thiosulphate to recover iodide again.
I3– 2 e- ⇌ 3 I-
S4O62– 2 e- ⇌ 2 S2O32–
I3– 2 S2O32– → S4O62– 3 I-
What Can go Wrong with Iodine Titrations?
There are some points to consider when conducting these reactions:
- In some cases, the product of the reaction can become reversible with a certain pH range, thus affecting the results. It’s essential that the pH of the sample solution is adjusted before the analysis.
- The volatility of iodine can become another source of error in the analysis. The best way to minimise this problem is to always ensure iodine is present in excess and the solution is kept at a low temperature.
- Other factors that may alter the final result are strong light, or the presence of copper or nitrite ions, which catalyse the conversion of iodide to iodine. Both these substances need to be removed before analysis.
- For prolonged reactions, it’s recommended to add dry ice to the reaction to prevent oxidation by exposure to air.
Free Technical Advice
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