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本文研究了在没有动物胶的0.5M H_2SO_4溶液中镉离子的极谱行为,得到了如下的结果:(1)在0.050～20.0mM CdSO_4+0.5M H_2SO_4的十种溶液中测得的电流-电位曲线都有良好的波形、恒定的极限扩散电流和易于确定的半波电位.这些曲线上都没有极谱极大出现;其极限扩散电流(波高)与镉离子的浓度成正比.在镉离子低浓度(0.050～0.20mM)时,半波电位保持不变,在镉离子高浓度(1.00～20.0mM)时,也仅有很小的变化.故镉离子在0.5MH_2SO_4,溶液中的电流-电位曲线可供定量和定性测定之用.(2)镉离子在低浓度时的极谱波是一种可逆波.(3)前人在H_2SO_4溶液中研究镉离子时之所以没有能得到令人满意的极谱行为的原因是他们在H_2SO4溶液中添加了动物胶的缘故.(4)作者从得到的波形良好的电流-电位曲线上,测定了25±0.2℃时镉离子在0.5M H_2SO_4溶液中的扩散电流常数、半波电位和电极反应中得失的电子数.结果如下: i_d/cm~(2/3)t~(1/6)=3.97μA/mM·mg~(2/3)·s~(-1/2) E_(1/2)=-1.011V(0.5M硫酸亚汞电极)=-0.559V(饱和甘汞电极) n=2 这些数据比Lingane的数据,扩散电流常数2.6μA/mM·mg~(2/3)·s~(-1/2)和半波电位-0.59V(饱和甘汞电极)],要合理些.
In this paper, the polarographic behavior of cadmium ions in 0.5M H 2 SO 4 solution without animal glue was studied. The results are as follows: (1) The current-potential measured in ten solutions of 0.050-20.0 mM CdSO 4 + 0.5 M H 2 SO 4 The curves have good waveforms, constant limiting diffusion current and easy-to-determine half-wave potentials. None of these curves exhibit extreme polarography; their limiting diffusion current (wave height) is proportional to the concentration of cadmium ions. (0.050 ~ 0.20mM), the half-wave potential remained unchanged, and only a small change in the high concentration of cadmium (1.00 ~ 20.0mM), so the current-potential in the solution of 0.5MH_2SO_4 The curve can be used for quantitative and qualitative determination. (2) The polarographic wave of cadmium ion at a low concentration is a kind of reversible wave. (3) The reason why cadmium ion was not satisfactorily studied in H_2SO_4 solution The polarographic behavior was due to the addition of animal glue to the H 2 SO 4 solution. (4) From the good current-potential curve obtained by the authors, the determination of cadmium ions in 0.5 M H 2 SO 4 solution at 25 ± 0.2 ° C. Diffusion current constant, half-wave potential and electrode reaction gain and loss of electricity The results are as follows: i_d / cm ~ (2/3) t ~ (1/6) = 3.97 μA / mM · mg ~ (2/3) · s -1 (1/2) E 1/2 = -1.011 V (0.5 M mercuric sulphate electrode) = -0.559 V (saturated calomel electrode) n = 2 These data are more accurate than the Lingane data for diffusion current constants 2.6 μA / mM · mg ~ (2/3) · s ~ (-1/2) and half-wave potential -0.59V (saturated calomel electrode)], to be reasonable.