Butane gas is copresses and used as liquid fuel in dispossble cigarette lighter and light weight camping stoves. Suppose a lighter contains 2.74ml of butane. d = 0.579g/ml a, How many gm of oxygen are needed to burn the butane completely-------gm O2 b, How many moles of H2O when all butene burns -------------------moles H2O c, How many total molcules of gas form when butane burns completely----------------molcules of gas.