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电导率的测定

电导率的测定. 安 排. 预习时，洗净玻璃器皿（ 1 支 100mL 量筒， 2 个分液漏斗， 7 支 25mL 比色管），一定要洗净，以免结果偏高。 检查分液漏斗，不得涂抹凡士林。 星期四上午每人带一瓶水样（湖水、饮用水，等）。 星期四上午萃取油，下午做电导率实验并进行油的测定。 星期四交上周的 2 份实验报告。. 2.3. Determination of Conductivity.

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电导率的测定

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  1. 电导率的测定

  2. 安 排 • 预习时，洗净玻璃器皿（1支100mL量筒，2个分液漏斗，7支25mL比色管），一定要洗净，以免结果偏高。 • 检查分液漏斗，不得涂抹凡士林。 • 星期四上午每人带一瓶水样（湖水、饮用水，等）。 • 星期四上午萃取油，下午做电导率实验并进行油的测定。 • 星期四交上周的2份实验报告。

  3. 2.3. Determination of Conductivity • Purpose: To understand the principle of conductivity measurement, and to master the usage of conductivity meter and monitoring method.

  4. Questions • What are the factors affecting the sample conductivity? • Total ion concentration, feature of the ions, temperature, viscosity • Why no preservation reagent can be added into the water sample? • It may change the conductivity.

  5. R: resistance L: distance A: area S: conductance P: resistivity K: conductivity Q: conductance constant S

  6. 1/R 0.001 mol/L KCl, standard det. K cal. K=1431 g/cm K=Q/R

  7. 8.紫外分光光度法矿物油的测定

  8. 2.10. Determination of Petroleum Purpose: • To understand the principle of petroleum determination. • To master one of the sample pretreatment methods, liquid-liquid extraction. • To get familiar with the operation of UV-Vis spectrophotometer.

  9. Determination Methods UV method: • All the compounds absorbing 220-225nm lights will be counted as petroleum – overestimated Florescence method • Only the compounds absorbing and emitting certain lights can be counted as petroleum – underestimated

  10. Determination Wavelength Petroleum – hydrocarbons • Alkenes (higher than 214 nm) • Aromatic (about 254 nm)

  11. Extraction • One of the separation methods • Liquid-liquid (L-L) extraction, liquid phase • Solid phase extraction (SPE) • Solid phase micro extraction (SPME)

  12. Procedure • L-L extraction with cyclohexane: acidizing, partition, separation 2. Determination with UV: organic phase, dry, absorbance, wavelength 3. Data processing one calibration curve for one group, one sample for each student

  13. Additional Questions • Should the solutions of the calibration curve be extracted as the samples? And why? • Discuss the possible deviation and error of this experiment.

  14. Attention！ • 用萃取剂把取样的量筒漂洗过，并入分液漏斗。 • 萃取液回收！ • 萃取液定容后，加无水硫酸钠脱水。 • 绘制工作曲线，不过原点。

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