Share
Notifications

View all notifications

Describe the Preparation of Potassium Dichromate from Iron Chromite Ore. What is the Effect of Increasing Ph on a Solution of Potassium Dichromate - Chemistry

Login
Create free account


      Forgot password?
ConceptSome Important Compounds of Transition Elements - Oxides and Oxoanions of Metals

Question

Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

Solution

Potassium dichromate is prepared from chromite ore (FeCr2O4) in the following steps.

Step (1): Preparation of sodium chromate

`4FeCr_2O_4 + 16NaOH+7O_2 -> 8Na_2CrO_4+2Fe_2O_3+8H_2O`

Step (2): Conversion of sodium chromate into sodium dichromate

`2Na_2CrO_4 + conc.H_2SO_4 -> Na_2Cr_2O_7 + Na_2SO_4 + H_2O`

Step(3): Conversion of sodium dichromate to potassium dichromate

`Na_2Cr_2O_7 + 2KCl -> K_2Cr_2O_7 + 2NaCl`

Potassium dichromate being less soluble than sodium chloride is obtained in the form of orange coloured crystals and can be removed by filtration.

The dichromate ion `(Cr_2O_7^(2-))` exists in equilibrium with chromate `(CrO_4^(2-))` ion at pH 4. However, by changing the pH, they can be interconverted.

  Is there an error in this question or solution?
Solution Describe the Preparation of Potassium Dichromate from Iron Chromite Ore. What is the Effect of Increasing Ph on a Solution of Potassium Dichromate Concept: Some Important Compounds of Transition Elements - Oxides and Oxoanions of Metals.
S
View in app×