Method of Analysis for Copper Oxide

1. Description

A black fine powder.

2. Solubility

Dissolve 2gm of the sample on a steam bath with a mixture of 5ml of HCl & 5ml of water. The solution should be clear.

3. Identification

Take about 20 to 50mg of the sample, add 5ml of 2M HCl. Heat the solution in the water bath to dissolve it. Add Potassium Ferro cyanide solution (5%). Insoluble reddish brown precipitates yielded.

4. Chloride

Limit: Not more than 0.1% w/w.
Reagents Required
Dilute nitric acid
Silver nitrate
Standard Chloride solution (1ml = 0.1mg of Cl)
Procedure: Dissolve 0.1gm in warm 2ml dilute nitric acid & dilute to 50ml with water and add 1ml of Silver nitrate solution. Any opalescence produced is not more than equally treated against 1ml of standard chloride solution (1ml = 0.1mg Cl)

5. Sulfate

Limit: Not more than 0.06%
Reagents Required
Hydrochloric acid
Nitric acid
Barium chloride
Procedure: To 5gm of sample add a mixture of 15ml of HCl & 15ml of water and 5ml of Nitric acid and evaporate to dryness on the steam bath. Dissolve the residue in 100ml with water and 1ml of HCl and filter. Heat the filtrates to boiling add 5ml of Barium chloride solution and allow to stand overnight. If a precipitate is present in filter, wash it well with water and ignite. Cool & calculate the weight of residue in percentage with reference to sample taken.
                          Wt. of Sulphate present in sample
% of Sulphate = ---------------------------------------------- X 100
                           Wt. of Sulphate present in standard

6. Iron

Limit: Not more than 0.1%
Reagents Required
Dilute Hydrochloric acid
Ammonium thiocyanate
6% w/v Hydroxyl Ammonium Chloride
Ascorbic acid
1,10-Phenanthroline solution
Sodium Acetate
Ammonia Solution
Standard Iron solution (1ml = 0.01mg Fe)
Procedure: Dissolve 1gm sample in 10ml of hot dilute hydrochloric acid and add 40ml of water and add 15ml of 7% ammonium thiocyanate solution, 15ml of 6% w/v solution of Hydroxyl Ammonium Chloride, mixing after each addition. Heat on the steam bath for 15 minutes. Cool to room temperature, set aside for 10 minutes and filter through weighed No. 4 porosity sintered glass crucible, dilute the filtrate to 100ml with water and retain for Fe test.
To 1ml filtrate add 0.5gm of Ascorbic acid, 10ml of 1,10-Phenanthroline solution and 0.5gm Sodium acetate (Trihydrate) adjust to pH between 4 and 6 with dilute ammonia solution and dilute to 50ml with water. Compare any red color produced with those obtained when 1ml of standard Iron solution (1ml = 0.01mg Fe) is used in the same manner.

7. Assay

Limit: Not less than 97%.
Reagents Required
Orthophosphoric acid
Potassium Iodide
0.1N Sodium Thiosulphate
Procedure: Dissolve about 0.3gm of the sample with heating in a mixture of 5ml of Orthophosphoric acid and 15ml of water-cool & add 3gm of Potassium Iodide. Stopper immediately and Titrate liberated iodine with 0.1N Sodium Thiosulphate solution using the starch solution as an indicator towards the end point.
1ml of 0.1N Sodium Thiosulphate solution = 0.007955gms of Copper oxide.
Calculation
                                      BR X Actual molarity X 0.007955 X 100
% of Copper oxide = ----------------------------------------------------
                                             0.1 X Wt. Of sample

BR= Burette Reading