英文版化学实验报告
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Determination of sodium chloride in saline
Purpose
Learning Silver nitrate standard solution preparation and calibration methods
Master Fajans method for the determination of chloride ions principle
Principle
In the PH value of 7-10.5, with fluorescent yellow as indicator, titration with AgNO3 standard chloride solution.Fluorescent yellow first dissociation in solution
HFIn ==== H++FIn−
Before the end of excess chloride ions, chloride ions adsorbed silver chloride precipitation, the negatively charged surface, the equivalence point of excess silver ions to precipitate silver ions adsorbed positively charged surface. Precipitation of positively charged anion adsorption fluorescent yellow indicator dissociated, the configuration time change colors green and yellow to pink.
AgCl ·Ag+ + FIn−===== AgCl ·Ag+· FIn−Laboratory instruments and reagents
Instruments and Materials:Acid burette(50ml), conical flask(250ml), volumetric flasks(100ml), pipettes25ml,10ml), graduated
cylinders(100ml,10ml), beakers(100ml), brown reagent bottles(500ml), analytical balances, scales.
Reagents and Drugs:Silver nitrate (analytical grade) sodium chloride (AR), saline, fluorescent yellow - starch indicator
Experimental Procedure
1.Take 25.00ml silver nitrate(C=0.07064mol/L) standard solution in
250ml volumetric flask, diluted with water to volume, shake, spare 2.Take the test specimen 10.00ml saline solution plus water in a conical
flask 50ml, fluorescent yellow indicator 3 drops of 5% starch solution 5ml, was diluted to the above standard solution of silver nitrate
titration, yellow-green to orange as the end point, measured parallel Third, calculate the mass density of the brine solution of sodium
chloride in the sample solution and the relative average error. Experimental data and processing
ρ1=C(AgNO3)V(AgNO3)M(NaCl)/10=0.07064×22.68×58.44／10=9.363g/L ρ2=9.371g/L ρ3=9.367g/L Averageρ=9.367g/L
dr=2.667×10-3Average dr=0.028%
Questions
Why the preparation of silver nitrate solution to be stored in a brown bottle and placed in the dark to save?
Explain:Silver nitrate precipitates metallic silver when exposed to light, so you need to save in a brown bottle.