CN101105487A

CN101105487A - Capillary burette gravimetric titration method

Info

Publication number: CN101105487A
Application number: CNA2007100661019A
Authority: CN
Inventors: 蔡成翔
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-08-09
Filing date: 2007-08-09
Publication date: 2008-01-16

Abstract

The invention belongs to the chemical analysis field and relates to a general and rapid mini type weighing titrimetry analysis method; the invention is characterized in that a common dull polish titrimetry device is substituted by the simplest and most cheapest capillary drip tube (the quality of drop liquid is 0.005-0.02g); a mechanical analysis scale is substituted by an electronic scale; the volume of a titrant solution is substituted by the quality of the titrant solution, and the contents of measured ingredients is calculated; the invention simplifies the device, lowers cost, is easy for operation and is in favor of the rapid capitation of a liquid reagent; the method in the invention is more convenient and more swift than the common weighing titration method and the general volume titration method. The key points of the method in the invention are as follows: a measured liquid in certain quality (or certain volume) is provided in a taper bottle (or a small beaker); the quality of the capillary drip tube is known, and the capillary drip tube absorbing a standard solution is used to drip the measured liquid (a magnetic force blender can be used); the quality of the capillary drip tube is weighed again when the capillary drip tube dripps at the end of the scale; the difference between the qualities of the capillary drip tube weighed at the two times is the quality of the consumed standard solution, according to which the contents of the measured ingredients can be calculated out.

Description

Capillary burette gravimetric titration method

Technical field

The invention belongs to chemical analysis field, relate to a kind of miniature weighing titrimetry method, be applicable to that composition quality mark to be measured is greater than 1% analysis project.

Background technology

Analysis by titration grew up in the mid-eighteenth century, and it comprises gravimetric titration method and volumetric precipitation method two big branches: the weighing analysis by titration of initial invention utilizes balance to determine solution quality, and calculates the content of measured object with this; This method accuracy height, the I of error at measurment reaches 0.03%, but machinery is raised the price analytical balance and special-purpose weighing titration apparatus operation loaded down with trivial details, finding speed is slow, only is applied in the mensuration work of primary standard substance or standard substance at present.The volumetric precipitation method of Chu Xianing is with glass volumetric apparatus such as buret metering liquor capacity subsequently, accelerated titrimetric speed greatly, although the accuracy of this method slightly reduces, the least error of measuring is 0.1%, but can satisfy general mensuration requirement, therefore occupy titrimetric leading position very soon.Even to this day, instrumental analysis such as photometric titration, conductance titration, potentiometric titration have enlarged the range of application of analysis by titration, but its reagent consumption is final expression-form with volume still mostly, still belongs to the volumetric precipitation method category.

Summary of the invention

The objective of the invention is, washing inconvenience too complicated at the isolated plant structure of common gravimetric titration method, operation is loaded down with trivial details, finding speed is slow, reagent consumption is big and a kind of miniature weighing titrimetry method of formulation.Be characterized in:

1, is that the capillary burette of 0.005～0.02g replaces common ground weighing titration apparatus with the drop size, simplified experimental provision;

2, the washing of capillary burette and operation are all easier, can alleviate tester's labour intensity;

3, replace the machinery analytical balance of raising the price with electronic analytical balance, make the weighing process reduce to the several seconds by several minutes, accuracy height and good stability if utilize its " peeling automatically " function, are operated also convenient.And in volumetric precipitation method, after buret is loaded onto or emitted solution, must wait 1～2min earlier, make after under the flow of solution of inwall and could begin reading, reading need spend about 0.5min again, and volume numerical value equals the poor of twice buret reading numerical value, so accumulative total is 4min before and after the time.Obviously, the finding speed of capillary burette gravimetric titration method is not only faster than common gravimetric titration method, and is better than conventional volumetric precipitation method;

Prove through test and uncertainty evaluation that 4, this law is when test substance content lower (＜20%) and titrant consumption amount are the 0.5g left and right sides, titration error is about 1%; When test substance content higher (＞90%) and titrant consumption amount during in the 5g left and right sides, titration error can reduce to 0.1%.Therefore can or measure the margin tolerance that is allowed and select suitable reagent dosage according to component concentration size to be measured;

5, the not only used capillary burette price extremely cheap (only 0.2～0.3 yuan /) of this method, and reagent dosage also has only 1/5～1/50 of macroprocedure, greatly reduces testing cost, and is special with the obvious advantage in the mensuration of gross sample;

6, this law is applicable to that composition quality mark to be measured greater than 1% analysis project, in fields such as commercial production control, analytical control, scientific research and teaching, all has vast market prospect and significant social economic benefit.

Embodiment

Embodiment 1

The Hardness Determination of industrial circulating cooling water

The pre-service of first step water sample is drawn a certain amount of water sample with pipette and is added in the 50mL conical flask, adds 3 sulfuric acid, 15 potassium persulfate solutions and 5mL water, and little fiery heated and boiled is done near.Be cooled to room temperature, add 5mL water, 8 triethanolamine solutions and 1 methyl red, shake up, use NH ₃-NH ₄Add 1mL again after the alkalization of Cl buffer solution, add 5mg eriochrome black T dry powder, stir with being placed on the magnetic stirring apparatus behind a small amount of distilled water flushing conical flask inwall.

Capillary burette tip after the Hardness Determination of the second step water will be equipped with the EDTA standard solution and dry surface moisture is placed upside down in the dry small beaker up, put into the electronic balance weighing in the lump, record numerical value drips EDTA solution until terminal point to the good water sample of pre-service behind the taking-up capillary burette.Once more capillary burette is placed upside down in weighing in the small beaker, difference is the consumption of EDTA solution, and the total hardness that can try to achieve this recirculated cooling water in view of the above is 1.93 (CaCO ₃Mmol/L), measurement deviation slightly is better than National Standard Method (GB/T15452-95) less than 1.2%.

Embodiment 2

Copper Determination on content in the aldary

First step aldary specimen preparation accurately takes by weighing aldary (H90) sample 2g, places small beaker, adds (1+1) HCl and 30%H ₂O ₂, heating for dissolving is also removed excessive H ₂O ₂After, being diluted to the sample solution gross mass is 100.0000g.

The second step copper Determination on content is drawn 2.0000g aldary sample, adds 5mL water, and dripping (1+1) ammoniacal liquor to solution has just had settlement to occur, and adds (1+1) HAc1.6mL and 200gL successively ^-1NH ₄HF ₂, 200gL ^-1Each 2mL of KI is with the 0.1molL that is equipped with of weighing ^-1Na ₂S ₂O ₃The capillary burette titration of standard solution adds 6～8 5gL to faint yellow ^-1Starch solution continues titration to light blue.Add 2mL100gL again ^-1NH ₄SCN, thermal agitation continues titration to blue the disappearance and is terminal point.Use the quality of electronic balance weighing capillary burette once more, difference is Na ₂S ₂O ₃The consumption of standard solution, the content that can try to achieve copper in this aldary in view of the above is 90.27%, measurement deviation is about 0.1%.

Claims

1. the present invention relates to a kind of general, miniature weighing titrimetry method fast, it is characterized in that:

(1) (drop mass is the common frosted weighing titration apparatus of 0.005～0.02g) replacement with simple, the most cheap capillary burette in laboratory;

(2) replace the machinery analytical balance of raising the price with electronic balance;

(3) replace volume of titrant in the hope of component concentration to be measured with the titrant quality;

The inventive method main points are as follows: the liquid to be measured of certain mass (or certain volume) is placed conical flask (or small beaker); Suction with a known exact mass has the capillary burette of standard solution to come titration liquid to be measured (can use magnetic stirring apparatus), titration weighing capillary burette quality once more to terminal the time, and difference is the standard solution quality of consumption, calculates component concentration to be measured in view of the above.