Chemistry Reference
In-Depth Information
0.505
0.50
0.495
0.49
0.485
0.48
0.475
0.47
0.465
0.46
0.48
1
1
3
2
2
0.43
3
0.38
0.33
4
4
0.28
0
100 200
Time (min)
300
0
100 200
Time (min)
300
(a)
(a)
0.51
1.1
1.0
0.50
0.49
1
0.48
2
0.9
1
0.47
2
3
0.8
0.46
3
0.45
0.7
0.44
0.43
0.6
4
4
0.42
0.41
0.5
0
100 200
Time (min)
300
0
100 200
Time (min)
300
(b)
(b)
1.6
0.53
0.51
1.5
0.49
1.4
1
0.47
2
1.3
1
3
0.45
1.2
0.43
2
1.1
0.41
3
1.0
0.39
0.9
4
0.37
4
0.8
0.35
0
100 200
Time (min)
300
0
100 200
Time (min)
300
(c)
(c)
11.2
Changes of solution concentration of Ni(II) and rongalite as a
function of time, with concentration ratio rongalite/Ni(II) of (a)
0.5/0.5; (b) 1.0/0.5; and (c) 1.5/0.5 and temperatures of (1) 298 K,
(2) 313 K, (3) 333 K and (4) 353 K.
in solution. These higher concentrations cause a greater inhibition effect,
and therefore the linear part of the initial decrease of the Ni(II) reduction
curve is shorter at higher temperatures.
Thirdly, the absolute amount of Ni(II) reduced in the reaction increases
with increasing rongalite concentration. From the complete set of data, it
was found that an optimum was obtained for
c
Rongalite
/
c
Ni(II)
= 3, and the
optimal value for the absolute concentrations was 0.5 mol l
-1
of Ni(II) and
1.5 mol l
-1
of rongalite. A low ratio is not favourable because of limited
Ni(II) in solution, while a ratio higher than 3 results in the formation of too
