GROUP VI 277
support the view that the hydrogen atoms are directly attached to
the phosphorus and are not present as hydroxyl, —OH, groups.
- As a starting material for other deuterocompounds. For
example deuterium oxide, on magnesium nitride, gives deutero-
ammonia, ND 3 ; with calcium dicarbide, deuteroethyne, C 2 D 2 , is
obtained.
On a larger scale, deuterium oxide has been used as a "moderator'
in nuclear reactors, having some advantages over graphite.Hydrogen peroxide, H 2 O 2Hydrogen peroxide is probably unique in the very large number of
reactions by which it is formed. Some of these may be mentioned :- From hydrogen and oxygen, by
(a) Burning hydrogen in oxygen and cooling the flame rapidly,
by directing against ice.
(b) By exposing hydrogen and oxygen to intense ultra-violet
light
(c) By exposure to certain radioactive rays, for example
neutrons or electrons. - By passage of a glow discharge through water vapour. This can
produce good yields of highly concentrated hydrogen peroxide
(cf. preparation of hydrazine). - By oxidation processes, for example oxidation of hydro-
carbons, fatty acids and even some metals. - By electrolytic oxidation (see below).
In many of the processes, it is believed that hydroxyl radicals,
OH % are formed and that some of these unite to form hydrogen
peroxide:
OH- + OH- -»HO:OHIn the laboratory, hydrogen peroxide can be prepared in dilute
aqueous solution by adding barium peroxide to ice-cold dilute
sulphuric acid:
BaO 2 + H 2 SO 4 -» BaSOJ -1- H 2 O 2The formation of an insoluble film of barium sulphate soon causes
the reaction to cease, but addition of a little hydrochloric acid or
better phosphoric(V) acid to the sulphuric acid allows the reaction
to continue.