Potassium Dichromate

Potassium dichromate with molecular formula and standarisartion

1. POTASSIUM DICHROMATE PresentedBy ; Anjana Paudel Chettri  Department ; B.pharmacy   

2. Contents Introduction   Preparation  Standardization Precaution

3. Introduction   Molecular Formula ; k 2 cr 2 o 7   Molecular weight   ; 294.18 gm\mol  General  PROPERTIES   Bright red orange crystalline solid.  It is odourless.  It is stable solid under normal conditions, but it decomposes upon heating to give potassium chromate and chromic anhydride with evolution of oxygen.                  

4. 4k 2 cro 4 + 2cr 2 3 + 30 2 4k 2 cr 2 7 USES   It is used for preparing strong cleaning solutions for glasswares and for etching materials.  Also used in leather tanning, photographic processing ,cement, and wood staining.  It is also used to prepare waxes ,paints ,glues e.t.c

5. Standardization To 20ml of the solution add 1gm of potassium iodide and 7ml of 2M hydrochloric acid (HCL).  Add 250 ml of water and titrate with 0.1 M sodium thiosulphate, using 3ml of starch solution,added towards the end point of the titration, as indicator until the colour changes from blue to light green.  1ml of 0.1 M sodium thiosulpate is equivalent to 0.0049 gm of potassium dichromate.

6. Precautions  As a hexavalent chromium compound, potassium dichromate is carcinogenic and highly toxic . It is also corrosive and skin\eye contact can cause severe irritation and burning sensation , even lead to blindness . Inorder to overcome the above hazards, precautions should be followed as given below……  While handling the chemical, should wear mask, gloves and glasses to avoid direct contact with chemical.  Accurate volume measurements should be taken'  The electronic balance should be calibrated before use.