1 Cm 3 Of Silver Nitrate Solution example essay topic

'We are provided with 3 salts X, Y and Z which contain a different's-block element. We are to carry out the reactions listed below and report the observations and deductions in the table. 1. Heat about 0.5 g of solid X in a clean dry test tube and test the gas evolved with a glowing splint. Continue heating until there is no further change and allow the residue to cool.

Observation Inference Lighted splint goes out when placed into test tube. Cannot be oxygen as the lighted splint would ignite and cannot be hydrogen, as the lighted splint would cause a popping sound. Could be carbon dioxide or another gas that causes the splint to goes out. 2.

Use a fume cupboard for this test. Add 2 cm 3 dilute hydrochloric acid to the cooled residue. Identify the gas evolved. Observation Inference Residue releases a brown gas The brown gas shows that nitrogen dioxide is present and so NO 3- ion must be present with the metal NO 3- ion.

The first 2 experiments show that X is a nitrate and the metal in X cannot be in group 2 as on heating a group 2 metal nitrate, would cause the compound to decompose to metal oxide, brown nitrogen dioxide and oxygen, this clearly did not happen until experiment 2 when HCl was added. The HCl reacted with the residue (Metal Nitrite) to give off metal chloride, nitrogen dioxide and water. 3. Make a solution of X in 5 cm 3-distilled water. Take half of this solution and add 1 cm 3 of silver nitrate solution followed by an equal volume of dilute nitric acid. Observation Inference Clear No halide ions present.

Experiment 3 is done in a different way then the usual method. The nitric acid is to remove any other compounds, which would interfere. The test solution is made acidic with dilute nitric acid to ensure the removal of carbonates or sulphate ions, which would interfere by giving a spurious precipitate, and then add the silver nitrate solution. A precipitate then forms.

4. Heat solid about 0.5 g of Y in a clean dry test tube and identify the gases evolved. Observation Inference Bubbles released and condensation appears to be present. Hydrogen is released but afterwards the limewater goes milky hence showing CO 2 is present.

The condensation shows that water is present. 5. Add 1 cm 3 of dilute hydrochloric acid to the cooled residue. Observation Inference Effervescence. Bubbles released (gas) Water is present. Metal Oxide + Hydrochloric Acid Water + Metal Chloride Test 4 and 5 shows that the elements oxygen, carbon, hydrogen and the metal are present.

The compound cannot be a carbonate because hydrogen is present. Therefore Y could contain HCO 3- ions. 6. Make a solution of about 0.5 g of solid Y in 5 cm 3 of distilled water and then take half of this and add 1 cm 3 of silver nitrate solution followed by an equal volume of dilute nitric acid. Observation Inference After Siler Nitrate Milky creamy After Nitric Acid Precipitate dissolves. No Halide ions present.

Usually in this experiment if the solution becomes cloudy after the silver nitrate it means there is a halide present. But like experiment 3, this experiment is done differently. Since you did not remove the carbonates, before adding the silver nitrate, the carbonates interfere by giving a spurious precipitate. By adding the nitric acid you remove the carbonates and the precipitate dissolves. If you first add the nitric acid to solution Y then add the silver nitrate, the precipitate would be clear showing that there is no halide ions. 7.

Make a solution of about 0.5 g of solid Z in 5 cm 3 of distilled water and then take half of this and add 1 cm 3 of silver nitrate solution followed by an equal volume of dilute nitric acid. Observation Inference After Siler Nitrate Milky creamy After Nitric Acid White precipitate Halide ion present. Br - ion present. Again like test 3 and 6 this experiment is done differently and has to be interpreted differently. The nitric acid removes any impurities so since this was added after the silver nitrate the halide ion present is Cl-. We can say if you add the nitric acid then the silver nitrate the precipitate would be white, and the white precipitate shows that chlorine ions are present.

8. Carry out the flame test to identify the cations in X, Y and Z. Observation Inference X Lilac Y Orange / Yellow Z Brick Red K+ Na+ Ca+ The heat energy of the flame causes electrons to be excited within the metal atoms hence raising them to a higher energy level. When these electrons return to the lower energy levels they emit characteristic colours. Group 1 Lithium Carmine red Flame colours of the S-block elements. Sodium Yellow Potassium Lilac Group 2 Calcium Brick Red Strontium Crimson Red Barium Apple Green Formulae of: X = KNO 3 Y = NaH CO 3 Z = CaCl 2 Potassium Nitrate Sodium Hydro Carbonate Calcium Chloride Chemistry.