Question

A mixture of `SO_(3) , SO_(2) and O_(2)` gases is maintained at equilibrium in 10 litre flask at a temperature at which `K_(c) " for the reaction ," 2SO_(2) (g) + O_(2) (g) hArr 2 SO_(3) (g) " is 100 mol"^(-1) ` litre. At equilibrium .
(a) if no. of moles of `SO_(3) and SO_(2)` in the flask are same, how many moles of `O_(2)` are present ?
(b) if no. of moles of `SO_(3)` in the flask are twice the number of moles of `SO_(2)` in the flask are twice the number of moles of `SO_(2)` , how many moles `O_(2)` are present ?

Answer 1

` 2 SO_(2) (g) + O_(2) (g) hArr 2 SO_(3) , " " K_(c) = ([SO^(2)])/([SO_(2)]^(2)[O_(2)] = 100)(Given)`
(a) As ` [ SO_(3)] = [ SO_(2)] , :. 100 = 1/([O_(2)]) or [O_(2)] = 1/ 100 molL^(-1)`
`:. O_(2) " present in 10 litre " = 1/100 xx 10 = 0*1 ` mole
(b) If ` [ SO_(3) ] = 2 [ SO_(2)] , i.e, ([SO_(3)])/([ SO_(2)] )= 2 " then " 100 = 4/ ([O_(2)] ) or [O_(2)] = 4/100 "mol"L^(-1)`
` :. O_(2) " present in 10 litre " = 4/100 xx 10 = 0*4` mole