Question

Which of the following conditions is the most suitable for the manufacture of sulphuric acid in contact process?

• A. High temperature and high pressure
• B. Low temperature and high pressure
• C. High pressure and low temperature
• D. Low pressure and low temperature

Answer 1

The correct option is B Low temperature and high pressure

$2S{O}_2+O_2\stackrel{V_2{O}_5}{\rightleftharpoons }2S{O}_3{\Delta }_{r}H=-196.6kJ/mol$
Since the forward reaction is exothermic, lower temperature will favor higher yield. This is in accordance with the Le Chatelier’s principle that an equilibrium tends to attain its original form when external conditions are changed.
Since the number of gaseous products are less than that of reactants, increasing pressure will also increase the yield.