Question

sodium is heated in excess of air, free from CO2 at 350 C to form X. X absorbs CO2 and forms Na2CO3 and Y. 'X' and 'Y' are respectively. plz do explain me this qstn and plz tell me tht all these kinds of qstns are done in the same way?

Answer 1

Sodium is heated in excess of air, free from CO2, at 350°C, to form sodium peroxide (X). X absorbs CO2 and forms Na2CO3 and oxygen (Y).

• Sodium reacts with excess of air, free from CO2, means, sodium reacts with excess of oxygen.

For step 1,

2Na + O2 (excess) +350°C → Na2O2 (X)

• Sodium reacts with oxygen to first form sodium oxide at a temperature of around 200°C.

• On further heating to 350°C, sodium being larger in size does not have a positive field strong enough to prevent the further oxidisation of oxide into peroxide, but strong enough to prevent the formation of superoxide.

• Therefore, Na2O2 is formed at 350°C.

For step 2,

2Na2O2 + 2CO2 → 2Na2CO3 + O2 (Y)

• Sodium peroxide is as an oxidising agent.

• It absorbs carbon dioxide and oxidises it to oxygen, thereby itself getting reduced to sodium carbonate.

NOTE - All such reactions can be solved in a similar manner. For this, you need to be thorough with the reactions and the conditions at which they take place. Go through the details and try to understand the concept behind the reactions. Read your text book thoroughly. It would help.