NEET 2021 | ऐल्कोहॉल, फीनौल एवं ईथर - L7 | Class 12 रसायन विज्ञान | Hindi Medium | Kamesh Sir | 4 PM

In iodometric titrations, an oxidizing agent such as KNnO_(4), K_(2)Cr_(2)O_(7),CuSO_(4),H_(2)O_(2) is allowed to react in neutral medium or in acidic medium with excess of potassium iodide to liberate free iodine Kl+ oxidizon agent to l_(2) Free iodine is titrated against stanard reducing agent usually with sodium thiosulphate i.e., K_(2)Cr_(2)O_(7)+6Kl+7H_(2)SO_(4)toCr_(2)(SO_(4))_(3)+4K_(2)SO_(4)+7H_(2)O+l_(2) 2CuSO_(4)+4Kl to Cu_(2)l_(2)+2K_(2)SO_(4)+l_(2) l_(2)+Na_(2)S_(2)O_(3)to 2Nal+Na_(2)S_(4)O_(6) In iodometric titrations, starch solution is used as an indicator. Starch solution gives blue or violet colour with free iodine. At the end point, blue or violet colour disappear when iodine is completely changed to iodide. A 1.1g sample of copper ore is dissovled and Cu^(2+) (aq.) is treated with Kl.l_(2) liberated required 12.12mL of 0.1M Na_(2)S_(2)O_(3) solution for titration. The % Cu in the ore in the ore is:

The length , breadth and height of a rectangular block of wood were measured to be l = 13.12 pm 0.02 cm, b = 7.18 pm 0.01 cm, h = 4.16 pm 0.02 cm The perecentage error in the volume of the block will be .

Class 12 Physics (Hindi) | Chapter 4 गतिमान आवेश एवं चुम्बकत्व | Important Questions and Quick Revision