What type of chemical reaction takes place a white salt on heating decomposes to give brown fumes?

A white compound on heating decomposes to give brown fumes and a yellow residue is left behind . Name the compound . Write the chemical equation of the reaction stating it's type ?

Posted by Jahanvi Choudhary 5 years, 1 month ago

The chemical name of white compound is Lead nitrate Pb(NO3)2.

The  compound on heating produces brown fumes. This implies that it contains nitrate ion. This  can be any nitrate but if the residue left after heating is yellow in colour implies that it is lead nitrate.

The type of  reaction is decomposition which is  shown as:

2Pb(NO3)2 → 2PbO + 4NO2 + O2

(i) LEAD NITRATE [Pb(NO3)2]

(ii) EQUATION :

2Pb(NO3)2(S) ----HEAT----> 2Pbo(S)+4NO2(G)+O2(G)

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Reddish brown gas is liberated from the white solid indicating that its nitrogen dioxide. 

The yellow solid residue is lead oxide.So the white solid is lead nitrate 

1. White solid is lead nitrate - Pb(NO3)2
2. This reaction is the decomposition reaction.2Pb(NO3)2 →2 PbO + 4 NO2 + O2
3. The gas liberated is reddish brown which is nitrogen dioxide and the other gas is oxygen
4. Since on dissolution it gives nitric acid the pH value is less than 72 NO2 + H2O → HNO3 + HNO2 
5. The residue left is lead oxide which is yellow in colour.

This was thermal decomposition reaction

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A white salt on heating decomposes to give brown fumes and a residue is left behind.i Name the salt.ii Write the equation for the decomposition reaction.