Laboratory Preparation for Carbon (ii) Oxide [CO] by keypoint It is formed when carbon (iv) oxide is passed through red-hot carbon or coke. CO2(g) + C(s) → 2CO(g) Laboratory Preparation for Carbon (ii) Oxide [CO]The conc. NaOH is used to remove any CO2 that is still present in the system. Others are Viewing: Carbon (ii) Oxide [CO] Laboratory Preparation of CO2 Carbon Allotropes of Carbon Carbon Black (Soot) Oxides of Carbon Method of Salt Preparation