chemical elements and their compounds - Sciencemadness Dot Org

Monatomic Hydrogen 17
atmosphere 21 ; according to v. Wartenberg 22 the temperature of the flame
near the electrode, as judged by the reversal of the spectral lines in comparison
with those of the sun, is 4,600-4,800°. From the heats of reaction
(H+H = H2+103-4 k.cals.; 2H2+02 = 2H20+116 k.cals.) it follows
that for equal volumes atomic hydrogen is 34 per cent, more efficient than
1 Knallgas', and for equal weights it is 24 times as effective.
In the gas the rate of recombination is much slower. A collision of two
hydrogen atoms cannot of itself lead to the formation of a molecule,
because the resulting pair cannot get rid of the energy of reaction, and so
must separate again; it is only fruitful when there is a three-body collision
2H + M -> H2M -> H2 + M,
no that the energy can be removed as kinetic energy of the H2+M (where
M of course may be the wall); this difficulty arises in all reactions of
HHBOciation or addition. Various determinations of the rate of recombination
of hydrogen atoms 23 have confirmed this view, and have shown that
the rate is that required by the triple-collision theory; the half-life of the
atoms is about 1 sec. at 0*2 mm, pressure.
The chemical reactions of atomic hydrogen are numerous, and have been
the subject of many investigations. 24 "" 41
Atomic hydrogen is a strong reducing agent. 25 It converts oxygen into
hydrogen peroxide 26 ' 27 ; it reduces ethylene to ethane 27 ; it reduces oleic
aoid C8H17- CH=CH (CHg)7COOH to stearic, but leaves the carboxyl
11
T. Langmuir, Science, 1925, 62, 463; Gen. Electric Review, 1926, 29, 153, 160.
|g
H. v. Wartenberg and H. J. Reusch, Nach. Ges. Wise. GoU. 1934, [ii] 1, 141.
" (a) Z. Bay and W. Steiner, Z. physikal Ghem. 1929, B 2, 146; (b) H. Senftleben
fttui O. Riechemeier, Naturwiss. 1930, 18, 645; (c) K. G. Emeleus, R. W. Lunt, and
0, A. Meek, Proc. Roy. Soc. 1936, 156, 394; (d) Lunt and Meek, ib. 157, 146;
(g) Lunt, Meek, and E. C. W. Smith, ib. 1937, 158, 729; (/) H. G. Poole, ib. 1937,
16I1 404; (g) id., ib. 415; (h) id., ib. 424.
" K. F. Bonhoeffer, Z. physikal Ghem. 1924, 113, 199.
M Id,, ib. 1925, 116, 391.
•• JiJ. Boehm and K. F. Bonhoeffer, ib. 1926, 119, 385.
w H. S. Taylor, J.A.G.8. 1926, 48, 2840.
M F. Haber and H. D. v. Schweinitz, Sitzb. Preuss. Akad. 1928, 499.
•» H. C. Urey and G. I. Lavin, J.A.G.S. 1929, 51, 3286.
10
E. Pietsch, F. Senferling, W. Roman, and H, Lehl, Z. Elektrochem. 1933, 39,
§77.
•* K. H. Geib and P. Harteek, Ber. 1932, 65, 1550, 1551.
•• P. Harteek, ib. 1933, 66, 423.
•• K. H. Geib and P. Harteek, ib. 1815.
M ld.# Z. physikal Ghem. 1934, 170, 1.
11
H. Kroepelin, E. Vogel, and H. Pfeiffer, Ber. 1935, 68, 684.
•• K. H, Geib and P. Harteek, Trans. Far. Soc. r034, 30, 131.
•* H. Kroepelin and E. Vogel, Z. anorg. Ghem. 1936, 229, 1.
11
P. Harteok and E. Roeder, Z. physikal Ghem. 1937, 178, 389.
•• P. Harteok and K. Stewart, ib. 181, 183.
•• J, JC, Dixon, JA.G.S. 1932, 54, 4262.
** J, P. W. Houtman, K. van den Berg, and P. M. Heertjes, Rec. Trav. 1943,
lii 671.
Nil n