Reactiile chimice:
x............x..............x............x
CH4 + Cl2 => CH3Cl + HCl
y............2y...............y..............2y
CH4 + 2Cl2 => CH2Cl2 + 2HCl
z............3z..............z.............3z
CH4 + 3Cl2 => CHCl3 + 3HCl
w...........4w...........w..........4w
CH4 + 4Cl2 => CCl4 + 4HCl
x/y = 4/2 => y=2x/4 = 0,5x
x/z = 4/2 => z=2x/4
x/w = 4/1 => w=x/4
x+y+z+w = 9 <=> x+2x/4+2x/4+x/4 = 9 <=> (4x+2x+2x+x)/4 = 9 <=> 9x/4 = 9 => x=9*4/9 = 4
y = 2 , z=2 , w=1
x+2y+3z+4w = 4+2*2+3*2+4*1 = 18 moli Cl2
CH4;Cl2 = 9:18 = 1:2