CONTENTS
- ESTIMATION OF BARIUM AS BARIUM SULPHATE
- ESTIMATION OF SULPHATE AS BARIUM SULPHATE
- ESTIMATION OF LEAD AS LEAD CHROMATE
- ESTIMATION OF CALCIUM AS CALCIUM OXALATE
- ESTIMATION OF BARIUM AS BARIUM CHROMATE
S. NO. | Details of Material Weighed | Crucible A g | Crucible B g |
01 | Weight of empty crucible (a) | ||
02 | Weight of crucible + barium sulphate (b) | ||
03 | Weight of barium sulphate (b-a) |
1. ESTIMATION OF BARIUM AS BARIUM SULPHATE
AIM:
To estimate gravimetrically the amount of barium present in the whole of the given solution of barium chloride.
PRINCIPLE:
Barium is precipitated as barium sulphate by the addition of dilute sulphuric acid.
BaCl2 + H2SO4 → BaSO4 + 2HCl
The precipitated barium sulphate is dried, ignited in a silica crucible and weighed. From the weight of barium sulphate the weight of barium can be calculated.
233.36 g of barium sulphate contains 137.36 g of Barium.
PROCEDURE:
The given barium chloride solution is made up to 100ml in a standard measuring flask. 20ml of the made up solution is pipetted out into a 400ml beaker. About 5ml of 2N hydrochloric acid is added followed by 80 ml of distilled water. The solution is heated to boiling and a hot solution of 4N sulphuric acid (10 to 15ml) added drop by drop with constant stirring, till the precipitation is complete. The solution is boiled for about 5 minutes. The precipitate is allowed to settle and the supernatant liquid tested for complete precipitation by adding a few drops of hot 4N sulphuric acid through the sides of the beaker. The solution is kept hot (but not boiling) for half an hour in order to allow time for complete precipitation.
CALCULATION:
Crucible A:
Weight of empty crucible (a) = g
Weight of crucible + barium sulphate (b) = g
Weight of barium sulphate.
(b-a) (c) = g
233.36 g of barium sulphate contains 137.36 g of Barium
∴Weight of barium present in the whole of the given solution = ……… X 5
= ………..g
Crucible B:
Weight of empty crucible (a) = g
Weight of crucible + barium sulphate (b) = g
Weight of barium sulphate
(b-a) (c) = g
233.36 g of barium sulphate contains 137.36 g of Barium
∴Weight of barium present in the whole of the given solution = ……… X 5
= ………..g
The clear solution is decanted through an ash less filter paper (Whatman No: 40). The precipitate is washed with small portions of hot distilled water until the washings does not give a precipitate with barium chloride solution (Free from sulphate ions). The precipitate is the transferred completely into the filter. A policeman removes any particles sticking to the side of the beaker. Finally the precipitate is washed once again. After the water has completely drained off, the funnel is kept in the air-oven for drying. Meanwhile a clean, dry silica crucible is heated for about 15 minutes. It is then cooled in a desiccator and its weight is determined. The filter paper when dry is removed from the funnel with a dry hand. It is then folded into a small packet taking care that all open ends are closed and the precipitate is enclosed well in the packet. The packet is the placed pointing downwards in the weighed silica crucible.
The crucible is placed on a pipe clay triangle, partially covered with its lid and heated first with a low flame till the filter paper chars. The paper should not be allowed to catch fire, as this will result in the loss of fine particles. When the charring is complete, heating is continued until all the carbon is oxidized. When the Weight in the crucible is white the crucible is heated strongly for about half an hour. The crucible is allowed to cool. Then a drop of concentrated sulphuric acid is added and again heated. If there is any deposit of carbon on the lid, if should be heated separately by holding if in the flame with a pair of tongs. The crucible is then transferred in to the desiccator and cooled. When cold, the crucible is weighed. Heating, cooling and weighing are repeated till concordant results are obtained. A duplicate experiment is conducted simultaneously. From the weight of the precipitated barium sulphate, the weight of barium in the whole of the given solution is calculated.
RESULT:
The Weight of barium present in the whole of the given solution
Crucible (A) = …………g
Crucible (B) = …………g
S. No. | Details of Material Weighed | Crucible A g | Crucible B g |
01 | Weight of empty crucible (a) | ||
02 | Weight of crucible + barium sulphate (b) | ||
03 | Weight of barium sulphate (b –a) |
2. ESTIMATION OF SULPHATE AS BARIUM SULPHATE
AIM:
To estimate gravimetrically, the amount of sulphate present in the whole of the given solution of potassium sulphate.
PRINCIPLE:
Sulphate ions present in the given solution are precipitated in presence of dilute hydrochloric acid as barium sulphate by adding barium chloride solution.
K2SO4 + BaCl2 → BaSO4 + 2KCl
The precipitate is filtered, dried, ignited and weighed as barium sulphate. From the Weight of barium sulphate, the Weight of sulphate in the whole of the given solution is calculated.
233.36 g of Barium sulphate contains 96 g of sulphate.
PROCEDURE:
The given potassium sulphate solution is made up to 100ml in a standard measuring flask and 20ml of the made up solution is pipetted out into a 400ml beaker. About 5ml of 2N hydrochloric acid is added, followed by 80 ml of distilled water. The solution is heated to boiling and a hot solution of 5 % barium chloride (15 to 20ml) added drop by drop with constant stirring. The solution is boiled for about 5 minutes. The precipitate is allowed to settle and the supernatant liquid tested for complete of precipitation by adding few drops of hot 5 % barium chloride through the sides of the beaker. If precipitate is formed, further 2ml of hot barium chloride solution is added slowly; the precipitate is allowed to settle and tested again. The beaker is covered with watch glass. The solution is kept hot (but not boiling) for half an hour in order to allow time for complete precipitation.
CALCULATION:
Crucible A:
Weight of empty crucible (a) = g
Weight of crucible + barium sulphate (b) = g
Weight of barium sulphate
(b-a) (c) = g
233.36 g of barium sulphate contains 96 g of Sulphate
∴Weight of sulphate present in the whole of the given solution = ………X 5
= g
Crucible B:
Weight of empty crucible (a) = g
Weight of crucible + barium sulphate (b) = g
Weight of barium sulphate
(b-a) (c) = g
233.36 g of barium sulphate contains 96 g of Sulphate
∴Weight of sulphate present in the whole of the given solution = ………X 5
= g
The clear solution is decanted through an ash less filter paper (Whatman No: 40). The precipitate is washed with small portions of hot distilled water until the filtrate is free from chloride ions. The precipitate is then transferred completely into the filter paper. The particles adhering to the sides of the beaker and glass rod are removed by a policeman. Finally the precipitate is washed once again. After the water has completely drained off, the funnel is kept in the air-oven for drying. Meanwhile a clean, dry silica crucible is heated for about 15 minutes. It is then cooled in a desiccator and its weight is determined. The filter paper when dry is removed from the funnel with a dry hand. It is then folded into a small packet taking care that all open ends are closed and the precipitate is enclosed well in the packet. The packet is then placed pointing downwards in the weighed silica crucible.
The crucible is placed on a pipe clay triangle, partially covered with its lid and heated first with a low flame till the filter paper chars. The paper should not be allowed to catch fire, as this will result in the loss of fine particles. When the charring is complete, heating is continued until all the carbon is oxidized. When the Weight in the crucible is white the crucible is heated strongly for about half an hour. The crucible is allowed to cool. Then a drop of concentrated sulphuric acid is added and again heated. If there is any deposit of carbon on the lid, if should be heated separately by holding it in the flame with a pair of tongs. The crucible is then transferred in to the desiccator and cooled. When cold, the crucible is weighed. Heating, cooling and weighing are repeated till concordant results are obtained. A duplicate experiment is conducted simultaneously. From the weight of the precipitated barium sulphate, the weight of sulphate in the whole of the given solution is calculated.
RESULT:
The Weight of sulphate present in the whole of the given solution
Crucible (A) = …………g
Crucible (B) = …………g
S. No. | Details of Material Weighed | Crucible A g | Crucible B g |
01 | Weight of empty crucible (a) | ||
02 | Weight of crucible + Lead chromate (b) | ||
03 | Weight of Lead chromate (b –a) |
3. ESTIMATION OF LEAD AS LEAD CHROMATE
AIM:
To estimate gravimetrically the amount of lead present in the whole of the given solution of lead acetate.
PRINCIPLE:
The lead is precipitated as lead chromate by the addition of 4% potassium chromate in presence of diluted acetic acid. The precipitate is filtered in a sintered glass crucible, dried and weighed.
(CH3COO)2 Pb + K2CrO4 → PbCrO4 + 2 CH3COOK
From the weight of lead chromate, the weight of lead is calculated.
323.22 g of Lead chromate contains 207.21 g of lead.
PROCEDURE:
The given lead acetate solution is made up to 100ml in a standard measuring flask and 20ml of the made up solution is pipetted out into a 400ml beaker. About 5ml of diluted acetic acid is added followed by 80 ml of distilled water. The solution is heated to boiling and a hot solution of 4 % potassium chromate (15 to 20ml) added drop by drop with vigorous stirring. The solution is boiled for about 15 minutes. The precipitate is allowed to settle and the supernatant liquid must be yellow in colour. The completion of precipitation is tested by adding few drops of hot 4 % potassium chromate through the sides of the beaker. When the precipitation is complete, the supernatant liquid is filtered in a previously weighed sintered glass crucible. It is washed with hot water, dried at 1200C in a hot air oven. Then it is cooled and weighed. A duplicate is also conducted.
From the Weight of lead chromate, the Weight of lead present in the whole of the given solution is calculated.
CALCULATION:
Crucible A:
Weight of empty sintered crucible (a) = g
Weight of crucible + lead chromate (b) = g
Weight of lead chromate
(b-a) (c) = g
323.22 g of lead chromate contains 207.21 g of lead.
∴Weight of lead present in the whole of the given solution= ………X 5
= ………..g.
Crucible B:
Weight of empty sintered crucible (a) = g
Weight of crucible + lead chromate (b) = g
Weight of lead chromate
(b-a) (c) = g
323.22 g of lead chromate contains 207.21 g of lead.
∴Weight of lead present in the whole of the given solution= ………X 5
= ………..g.
RESULT:
The Weight of lead present in the whole of the given solution
Crucible (A) = …………g
Crucible (B) = …………g
S. No. | Details of Material Weighed | Crucible A g | Crucible B g |
01 | Weight of empty crucible (a) | ||
02 | Weight of crucible + alcium oxalate (b) | ||
03 | Weight of calcium oxalate (b –a) |
4. ESTIMATION OF CALCIUM AS CALCIUM OXALATE
AIM:
To estimate gravimetrically, the amount of calcium present in the whole of the given solution of calcium chloride solution.
PRINCIPLE:
The given calcium chloride solution is made up to a definite volume. Calcium present in a definite volume of the made up solution is precipitated as calcium oxalate monohydrate by adding ammonium oxalate solution.
CaCl2 + (NH4)2C2O4 + H2O → CaC2O4. H2O + 2NH4Cl
The precipitate is filtered using sintered glass crucible, washed dried and weighed. From the Weight of calcium oxalate, the Weight of calcium in the whole of the given solution is calculated.
146.08 g of calcium oxalate contains 40.08 g of calcium.
PROCEDURE:
The given calcium chloride solution is made up to 100ml in a standard measuring flask and 20ml of the made up solution is pipetted out into a 400ml beaker. A drop (or) two of methyl orange added and the solution is carefully neutralized by ammonium hydroxide. About 5 ml of dilute Hydrochloric acid is then added, followed by 80 ml of distilled water and heated to boiling. While continuously stirring, a moderate excess of a hot 2 % solution of ammonium oxalate (freshly prepared) is gradually added. The precipitation of the calcium oxalate is then completed by adding ammonium hydroxide drop by drop until the solution is alkaline. The solution is then boiled for a few minutes, care being taken to avoid bumping. It is then set aside for about an hour for cooling and settling of the precipitate.
CALCULATION:
Crucible A:
Weight of empty sintered crucible (a) = g
Weight of crucible + calcium oxalate (b) = g
Weight of calcium oxalate (b-a) (c) = g
146.08 g of calcium oxalate contains 40.08 g of calcium.
∴Weight of calcium present in the whole of the given solution =……. X 5
= g.
Crucible B:
Weight of empty sintered crucible (a) = g
Weight of crucible + calcium oxalate (b) = g
Weight of calcium oxalate (b-a) (c) = g
146.08 g of calcium oxalate contains 40.08 g of calcium.
∴Weight of calcium present in the whole of the given solution =…… X 5
= g.
The precipitate is then filtered through a sintered glass crucible. The precipitate washed three times by cold ammonia solution. (25ml of 2N ammonium hydroxide is diluted to 100 ml). The washing is continued until a portion of then filtrate gives no turbidity with silver nitrate solution and nitric acid.
Finally, the precipitate is washed three times with small quantities of alcohol and then with ether. The crucible is then placed in a hot air oven maintained at 100oC for half an hour. It is then cooled and weighed
From the Weight of calcium oxalate, the Weight of calcium present in the whole of the given solution is calculated.
RESULT:
The Weight of calcium present in the whole of the given solution
Crucible (A) = …………g
Crucible (B) = …………g
S. NO. | Details of Material Weighed | Crucible A g | Crucible B g |
01 | Weight of empty crucible (a) | ||
02 | Weight of crucible + barium chromate (b) | ||
03 | Weight of barium chromate (b-a) |
5. ESTIMATION OF BARIUM AS BARIUM CHROMATE
AIM:
To estimate gravimetrically, the amount of barium present in the whole of the given solution of barium chloride solution by precipitating it as barium chromate.
PRINCIPLE:
Barium is precipitated as barium chromate in acetic acid medium by the addition of potassium chromate.
BaCl2 + K2CrO4 → BaCrO4 + 2KCl
The precipitated barium chromate is filtered in a sintered crucible, washed, dried at 1200C and weighed as barium chromate.
253.34 g of barium chromate contains 137.36 g of Barium.
PROCEDURE:
The given barium chloride solution is made up to 100ml in a standard measuring flask. Exactly 20ml of the made up solution is pipetted out into a 400ml beaker. Exactly 1 ml of 6M acetic acid and exactly 10 ml of 3M ammonium acetate are then added followed by 80 ml of distilled water. The solution is heated to boiling in a water bath and to the hot solution 15-20ml of 4% potassium chromate solution is added slowly with constant stirring. The heating is continued for further 15 minutes and the precipitate is allowed to settle. The clear supernatant liquid must be yellow in colour. A little more 4% potassium chromate solution is added down the sides of the beaker into the supernatant liquid to test for completion of precipitation. When there is no turbidity, the precipitation is complete.
CALCULATION:
Crucible A:
Weight of empty crucible (a) = g
Weight of crucible + barium chromate (b) = g
Weight of barium chromate
(b-a) (c) = g
253.34 g of barium chromate contains 137.36 g of Barium
∴Weight of barium present in the whole of the given solution = ……… X 5
= ………..g
Crucible B:
Weight of empty crucible (a) = g
Weight of crucible + barium chromate (b) = g
Weight of barium chromate
(b-a) (c) = g
253.34 g of barium chromate contains 137.36 g of Barium
∴Weight of barium present in the whole of the given solution = ……… X 5
= ………..g
The clear solution is filtered in a previously washed crucible dried at 1200C. The precipitate is washed with hot water and the washings also are filtered by decantation. Washing and filtration is continued till the filtrate is free from chloride and chromate ions (tested with silver nitrate solution). The precipitation is then completely transferred into the sintered crucible. Any precipitate adhering to the sides of the beaker is removed using a policeman. When filtration is complete, 4 drops of ethanol are added to the precipitate and allowed to drain off. The crucible is the dried at 1200C for an hour in an air oven. It is then cooled in a desiccator and when quite cold it is weighed. The heating, cooling and weighing are repeated to constant weight. A duplicate experiment is conducted simultaneously. From the weight of the barium chromate precipitate, the amount of barium present in the whole of the given solution is calculated.
RESULT:
The Weight of barium present in the whole of the given solution
Crucible (A) = ………… g
Crucible (B) = ………… g