Question

Calculate the moles of pure KCLO3 present in X g of a sample of impure KCLO3 which on strong heating yeilds y mL of O2 at STP.

(Check the attachment for the question and the options)

Answer 1

Given : pure KClO3 present in X g of a sample of impure KClO3 which on strong heating gives y ml of O2 at STP.

To find : The number of moles of KClO3 present in X g of the sample of impure KClO3.

solution : here reaction is given ..

2KClO3 ⇔2KCl + 3O2

two moles of KClO3 form 3 moles of oxygen gas.

so, two moles of KClO3 form 3 × 22400 ml of oxygen gas at STP.

⇒y ml of oxygen gas is produced to heat 2y/(3 × 22400) mol of KClO3.

a/c to question,

y ml of O2 gas is produced to heat X g of impure KClO3 sample.

means, X g of impure KClO3 sample contains 2y/(3 × 22400) mol of KClO3.

so, the number of moles of pure KClO3 is 2y/(3 × 22400) = y/(33600) moles

Therefore option (1) is correct choice.