Use this to make a model answer.
Any one ______________ :
no heat required / works at room temperature so reduces energy cost
or no catalyst required reducing product purification costs / making purification easier / so no need to recover catalyst
or reaction is not an equilibrium / reaction goes to completion so produces a higher yield Any one disadvantage:
hydrogen chloride produced is acidic / corrosive so corrosion resistant plant/equipment required (which is more expensive)
or HCl is toxic so must use a fume cupboard / clean exhaust gases / capture the gas (for sale)