Chemical properties of oxygen compounds of nitrogen

2.1. Put 2 g of the crushed ammonium nitrate into a test tube, close with a stopper provided with an exhausting tube and heat cautiously. Do not heat salt above 170-180°, because in this case the mechanism of reaction is changed and other products are formed. The reaction proceeds with self-acceleration, therefore when reaction is accelerating it is necessary to reduce or stop heating temporarily. When air will be superseded from a test tube, collect the gas, which evolves in a test tube by a method of air replacement. How is the test tube to be placed? Put a decaying splinter into a test tube with gas. What can you observe? Does it support burning?

2.2. Put 0,5 g of copper sawdust into a test tube, add 2-3 mls of diluted nitric acid, close with a stopper provided with an exhausting tube and heat. When air will be superseded from the test tube, collect the gas, which evolves, in a test tube by the method of water replacement. Open the test tube with gas on air on a background of a white paper. What can you observe? Close the test tube, overturn it, load in an exsiccator with water and open under water. What can you observe? Add 1-2 drops of neutral litmus solution to the solution in the test tube. What can you observe? Give the equations of the relevant reactions.

2.3. Place 1-2 mls of sodium nitrate solution into a test tube and add 5-6 drops of diluted nitric acid solution. Why is the solution discoloured? What gas is collected over the solution?

2.4. Place 3-4 drops of 0,5N solution of potassium dichromate, 5-6 drops of diluted sulfuric acid into a test tube and add 4-5 drops of 0,5N solution of sodium nitrite. How and why is the solution discoloured? What properties does sodium nitrite show in this reaction? Give the equation of the reaction.

2.5. Place 1 ml of 0,5N potassium iodide solution, 7-8 drops of diluted sulfuric acid into a test tube and add 4-5 drops of 0,5N sodium nitrite solution. How and why is the solution discoloured? What properties does sodium nitrite show in this reaction? Give the equation of the reaction.

2.6. Place 3-4 drops of concentrated nitric acid into each of two test tubes and add: a slice of copper shaving into the first, a slice of tin into the other one, close with a stopper provided with an exhausting tube and heat. What can you observe? When the air will be superseded from a test tube, pass the gas which evolves in a test tube with water, and add 1-2 drops of litmus neutral solution to it. What can you observe? Give the equations of the relevant reactions and make a conclusion on chemical character of nitrogen (ІV) oxide.

2.7. Place 1-2 mls of concentrated hydrochloric acid into a test tube and add 4-5 drops of concentrated nitric acid. What can you observe? Put a strip of filter paper, moistened with solution of potassium iodide to an aperture of the test tube. What can you observe? Give the equations of the relevant reactions.

2.8. Put one microspatula of crystalline nitrate of potassium, manganese (ІV) oxide and potassium hydroxide into a dry test tube. Heat the test tube until mixture melts. What can you observe? Give the equations of the relevant reactions.

2.9. Put 3-5 crystals of copper (ІІ) nitrate into a dry test tube. Heat a test tube until mixture melts. What can you observe? Give the equations of the relevant reactions.

Дата добавления: 2015-11-14