Question

(i) Write two observations when lead nitrate is heated in a test tube.

(ii) Name the type of reaction.

(iii) Write a balanced chemical equation to represent the above reaction.

3

16 A compound ‘X’ of sodium is used as an antacid and it decomposes on strong heating.

(i) Name the compound ‘X’ and give its chemical formula.

(ii) Write a balanced chemical equation to represent the decomposition of ‘X’.

(iii) Give one use of compound ‘X’ besides an antacid.​

Answer 1

this reaction is called thermal composition reaction.

2NaHCO3-Na2CO3+H2O+CO2

Answer 2

• Observations when lead nitrate is heated in a test tube :

- A reddish brown gas is produced which is actually nitrogen dioxide or NO2.

- Colourless lead nitrate becomes yellowish lead oxide or PbO.

• Heating the lead nitrate is a thermal decomposition chemical reaction.

• Balanced chemical equation to represent the thermal decomposition of lead nitrate :

2Pb(NO3)2 = 2PbO + 4NO2 + O2

• The compound X is actually sodium bicarbonate or NaHCO3.

• Decomposition reaction of compound X :

2NaHCO3 = Na2CO3 + CO2 + H2O

• Besides an antacid,the sodium bicarbonate is also used for baking purposes.