Preparation of Potassium Nitrite

Preparation of Potassium Nitrite. Melt 1-2 g of potassium nitrate in a test tube and heat it above its melting point until oxygen bubbles stop evolving. Dissolve the cooled substance in water and add 1-2 ml of a dilute sulphuric acid solution. What happens  

Write the equations of the reactions. How can you prove that nitrous acid has formed in the solution  

What products form when potassium, copper, lead, or silver nitrates are roasted What explains the different nature of their decomposition  

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