Modern inorganic chemistry

ENERGETICS 81

produce B^3 + (g)—and in fact this ion is not found as such. In fact.
there is no sharp division between hydration and hydrolysis, since
hydrated multi-charged cations such as Al^3 + (aq), Fe3+(aq) do
undergo a loss of protons which is also a 'hydrolysis' (p. 45).

QUESTIONS

Or

500

1000

400 600 800 IOOO I200

Temperature, K

I400

1. (a) Describe how the use of Ellingham diagrams such as the one
   above helps to explain why metal oxides can be reduced by the
   use of
   (i) other metals,
   (ii) carbon,
   (iii) carbon monoxide.
   (b) Why is it necessary to use electrolysis for the extraction of some
   metals?
   (c) Why is it that the slope of the graph of free energy of formation
   of zinc oxide against temperature is as shown in the diagram,
   whereas the slope of the graph of free energy of formation of
   carbon monoxide against temperature has the opposite sign?
   (N,A)