Industrial and biological chemical reactions are controlled using different types of catalysts to alter reaction pathways and rates. Which of the following statements correctly describes the classification or mechanism of the specified catalyst?
In the industrial Contact Process, vanadium(V) oxide (V2O5V_2O_5V2O5) acts as a homogeneous catalyst to control the oxidation of SO2SO_2SO2 to SO3SO_3SO3 by changing its oxidation state in the gas phase.
In the catalytic converter of a combustion engine, platinum and rhodium act as heterogeneous catalysts that control emissions by reducing carbon monoxide (COCOCO) to solid carbon and oxidizing nitrogen monoxide (NONONO) to nitrogen dioxide (NO2NO_2NO2).
In the reaction between peroxodisulfate (S2O82−S_2O_8^{2-}S2O82−) and iodide (I−I^-I−) ions, aqueous Fe2+Fe^{2+}Fe2+ acts as a homogeneous catalyst by first being oxidized to Fe3+Fe^{3+}Fe3+ by S2O82−S_2O_8^{2-}S2O82−, and then reduced back to Fe2+Fe^{2+}Fe2+ by I−I^-I−.
An enzyme controls cellular reaction rates by acting as a heterogeneous catalyst, where the solid-state protein surface adsorbs gaseous substrates from the cytoplasm before releasing aqueous products.
31 exam-style questions on OCR GCSE Chemistry Controlling reactions. Each one has a worked solution and a mark scheme showing where the marks go.