Page 299 - Introduction to Colloid and Surface Chemistry

288 Answers

13. M T = 13000 (suggesting surface dissociation)
14. wA = 2RT (suggesting that hydrogen is dissociated into atoms
when chemisorbed on a nickel surface)
3 1
15. V m = 225 cm (s.t.p.) g'
5
a = 7.1 x Hr Pa~ l
2
16. 530 m g" 1
20 2
17. 47 x 10" m
2
1
18. 7.8 m g" (using BET equation)
19. V/V m 0.4 0.8 1.2
1
A// ads/kJ moP -11.8 -12.7 -9.1
Values reflect multilayer physical adsorption on a fairly uniform
solid surface

20. 0 = 0.1, A# ads = -180 kJ mol~ l
0 = 0.5, A// ads. = -123 kJ

Absolute magnitudes suggest chemisorption and relative magni-
tudes reflect preferential adsorption at the more active sites on
the solid surface
21. A/fad,. = -44 kJ moP 1
22. r = 2.03 nm (assuming zero contact angle, closed cylindrical
pores, constancy of y with r, equivalence of multilayer adsorption at
flat and curved surfaces)
23. (a) p/p 0 = 0.81; (b) plp 0 = 0.90
2
14
24. Fe(lOO), 12.2 x 10 atoms cm" ;
14
2
Fe(llO), 17.3 x 10 atoms cnT ;
14 2
Fe(lll), 7.1 x 10 atoms cm" ;
14
Fe(100)-C(2 x 2)-N, 6.1 x 10 N atoms cm~ 2
2
25. W a - 54.0 ml m~ , S = -91.5 mJ m~ 2
26. 69°
20
27. 145 x 10" m 2
28. (a) 1 nm; (b) 10 nm; (c) 7 nm; (d) 5 nm