Red Solution Clause Samples

Red Solution. Dissolve 60g of cobalt chloride R in about 900ml of a mixture of 25ml of hydrochloric acid R and 975ml of water, dilute to a 1000ml with the same mixture. Place 5ml of the solution, 5ml of dilute hydrogen peroxide and 10ml of 30% w/v sodium hydroxide into a 250ml ground glass stoppered flask. Boil gently for 10 minutes, allow to cool and add 60ml of dilute sulphuric acid and 2g of potassium iodide. Close the flask and dissolve the precipitate by shaking gently. Titrate the liberated iodine with standardised 0.1N sodium thiosulphate. Towards the end of the titration (about 12ml) add 0.5ml of starch indicator, continue the titration until the solution turns pink and an end point has been reached. Calculate the concentration of the solution using the following equation. mg/ml Co(11)Cl(2) = ml of Na(2)S(2)0(3) x N of Na(2)S(2)0(3) x 23.79mg/0.5ml Adjust the concentration to within 10% of 59.5mg of C0Cl(2)6H(2)0 per ml by diluting with 0.3N hydrochloric acid using the calculation below: ml of 0.3N hydrochloric acid per 100ml red solution = 100 - 5950 ----------------- mg/ml Co(11)Cl(2)