Question

73.5 gm of KClO3 is decomposed on heating as follow : 2KClO3 ----> 2KCl + 3O2 calculate the mass of KCl and volume of O2 formed at S.T.P

Answer 1

No. of moles = Mass/Mass of 1 mole 
= 73.5 g / 122.5 
= A (mole of kclo3) -----> solve the value of A


2 moles KClO3 produces 3 moles of O2 
therefore A moles KClO3 will produce 3/2 x A mole O2 
= B mole O2 

Volume of Gas= No. mole x stp (22.4dm3) 
= B mol x 22.4 dm3mol-1 
= C dm3 or L O2 



calculate you all values A,B,C

A = 73.5/122.5
B = 3/2 * A
C = B * 22.4 dm3mol-1