Question

How much potassium bromide should be added to perform formalin test?

Answer 1

Answer on Question #81947, Chemistry/ Organic Chemistry

How much potassium bromide should be added to perform formalin test?

Answer

The oxidation of formaldehyde and determination of the excess of the oxidizing agent is used as a means of estimation.

An alkaline solution of formaldehyde may be oxidized with bromine equivalent to the excess of bromine, that can be liberated from the acidified solution and titrated with sodium thiosulfate. A standard solution of potassium bromide – potassium bromate (0.1 N) is used for the production of bromine.

$$\mathrm{BrO_3^-} + 5\mathrm{Br^-} + 6\mathrm{H^+} \rightarrow 3\mathrm{Br_2} + 3\mathrm{H_2O}$$

To prepare standard solution one should dissolve 3 g of potassium bromated and 15 g of potassium bromide in water to make 1000 mL.

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