An equilibrium mixture ` CO(g) + H_(2) O (g) hArr CO_(2) (g) + H_(2) (g)` present in a vessel of one litre capacity at 1000 K was found to contain` 0*4 `mole of CO, `0*3 `mole of ` H_(2)O, 0*2 ` mole of `CO_(2) and 0*6 ` mole of `H_(2)`. If it is desired to increase the concentration of CO to `0*6 `mole by adding `CO_(2)` into the vessel , how many moles of it must be added into equilibrium mixture at constant temperature in order to get this change ?

Explanation

Step 1 . To calculate ` K_(c) ` of the reaction .
`K_(c) = ([CO(g) ] [H_(2) (g) ])/([CO(g) ] [H_(2)O(g)] ) = (0*2 xx 0*6)/(0*4 xx 0*3 ) = 1 `
Step 2. To calculate extra `CO_(2)` to be added
suppose extra ` CO_(2) ` to be added = x mole . Then writing the reverse reaction , we have
` {: (,CO_(2),+,H_(2)O,hArr,CO,+,H_(2)O), ("Intial moles",0*2 +x ,,0*6,,0*4,,0*3), ("after addition",,,,,,,),("Moles(Molar ",(0*2 +x-0*2),,(0*6 -0*2),,0*6,(0*3+0*2),),("conc.)at new ",=x,,=0*4,,("Given"),=0*5,(V= 1L)),("equilibrium ",,,,,,,("Increase in CO concentration")),(,,,,,,,=0*6 - 0*4 = 0*2):}`
` k_(c) = 1/K_(c) = (0*6 xx 0*5 )/( x xx 0*4) = 1 or x = 0* 75 " mole "`
` {:(,PCl_(5),hArr,PCl_(3),+,Cl_(2),),("Intial ",0*1 "mol",,,,,),("At eqm." ,0*1 -x,,x,,x,"Total no. moles at eqm. "= 0*1 +x):}`
` K_(c) = 1/K_(c) = (0*6 xx 0*5 )/(x xx0*4) = 1 or x = 0*75 " mole " `