数字电流表作为指零仪测定电解质溶液电导  

The Precise Digital Measuring Instrument as a Null Detector Determinates Conductivity of Electrolytic Solutions

作　　者：杨涛[1] 方文军[1] 冷文华[1] 刘迎春[1] 

机构地区：[1]浙江大学化学系,杭州310027

出　　处：《实验室研究与探索》2017年第1期59-61,共3页Research and Exploration In Laboratory

基　　金：国家自然科学基金项目(20876132)

摘　　要：用自制的精密数字电流表作指零仪测定电解质溶液的电导。实验装置由音频信号发生器、转盘电阻箱和精密数字电流表组成,将音频信号发生器频率设定在1 kHz,在实验测量过程中调节转盘电阻箱,当精密数字电流表上的数据显示最小时,电桥已达到平衡。测量0.02,0.02/2,0.02/4,0.02/8,0.02/16 mol/L氯化钾溶液电阻值,其中测得的0.02/16氯化钾溶液的电阻值为3.689 kΩ,计算的电导值为0.150 1 mS/m(文献值为0.149 8 mS/m),相对误差为0.20%。结果表明:用精密数字电流表作指零仪,可以精确到0.1,实验测量精度显著提高,相对误差较小,且观察直观、操作快捷、价格低、体积小。As a traditional null detector for measuring the conductance of electrolyte solution,the oscilloscope is limited because of lower measurement precision.The measurement accuracy is greatly improved by self-made precise digital measuring instrument.The experimental device is composed of oscilloscope,a resistance box and a precise digital measuring instrument.The frequency of oscilloscope is set in the 1 kHz range,the bridge balance is reached when the precise digital measuring instrument shows minimum value.The values of resistance R of the cell containing KC1 solutions are measured at concentrations C_a =0.02,0.02/2,0.02/4,0.02/8,0.02/16 mol/L.The determination value of R for 0.02/16 is 3.689 kΩ,the conductivity is 0.150 1 mS/m at 25 ℃（reference value is 0.149 8 mS/m）,the relative error is 0.20%.Experimental results show that the precise digital measuring instrument can work as a null detector,the value can be accurate to 0.1.Hence,experimental measurement accuracy is significantly improved,and the relative error is small.The advantage of the digital measuring instrument is intuitive observation,fast operation,low price,small size,and experimental efficiency has been improved in experimental teaching.

关 键 词：物理化学实验 精密数字电流表 电解质溶液 电导测定 

分 类 号：O6-32[理学—化学]