CN1804617A - Method for analyzing pH value - Google Patents
Method for analyzing pH value Download PDFInfo
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- CN1804617A CN1804617A CN 200510135529 CN200510135529A CN1804617A CN 1804617 A CN1804617 A CN 1804617A CN 200510135529 CN200510135529 CN 200510135529 CN 200510135529 A CN200510135529 A CN 200510135529A CN 1804617 A CN1804617 A CN 1804617A
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- Prior art keywords
- titration
- acid
- concentration
- solution
- alkali
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- 238000000034 method Methods 0.000 title abstract description 28
- 238000004448 titration Methods 0.000 claims abstract description 28
- 239000002253 acid Substances 0.000 claims abstract description 25
- 238000000954 titration curve Methods 0.000 claims abstract description 14
- 239000002585 base Substances 0.000 claims abstract description 11
- 239000003513 alkali Substances 0.000 claims abstract description 9
- 238000012888 cubic function Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 15
- 238000004458 analytical method Methods 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 3
- 238000005070 sampling Methods 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 abstract description 5
- 230000003301 hydrolyzing effect Effects 0.000 abstract 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- VMESOKCXSYNAKD-UHFFFAOYSA-N n,n-dimethylhydroxylamine Chemical compound CN(C)O VMESOKCXSYNAKD-UHFFFAOYSA-N 0.000 description 5
- 238000002479 acid--base titration Methods 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- JLDSOYXADOWAKB-UHFFFAOYSA-N aluminium nitrate Chemical class [Al+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O JLDSOYXADOWAKB-UHFFFAOYSA-N 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical compound [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- CEQFOVLGLXCDCX-WUKNDPDISA-N methyl red Chemical compound C1=CC(N(C)C)=CC=C1\N=N\C1=CC=CC=C1C(O)=O CEQFOVLGLXCDCX-WUKNDPDISA-N 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- WJWSFWHDKPKKES-UHFFFAOYSA-N plutonium uranium Chemical compound [U].[Pu] WJWSFWHDKPKKES-UHFFFAOYSA-N 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
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- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention provides a method for analyzing the pH value of a system with existence of hydrolytic ions or weak acid and weak base. The method uses a cubic function to fit a pH-chi titration curve pH ═ a chi3+bχ2+ c χ + z, x = -b/3a is the volume consumed by the acid/alkali solution with known concentration at the end point of titration, and the concentration of the alkali/acid solution to be measured is calculated according to the volume. The method can simply and accurately analyze the concentration of free acid and base or weak acid and weak base in the solution in the presence of hydrolytic ions。
Description
Technical field
The present invention relates to the analytical approach of acid base concentration in the organic analysis, specifically disclose a kind of method that the hydrolysis ion exists or weak acid and weak base system potential of hydrogen is analyzed that has.
Background technology
The principle of acid base titration is that the pH value of solution value has big hop before and after equivalent point.Based on this point, the developer that general employing can color changes in titration pH mutation range is used as indicator, the advantage of this method be easy fast.But for situation about being not suitable for developer, people adopt V～Δ pH/ Δ V method more, the amount that is consumed when the volume of the vs that consumes is titration end-point when getting Δ pH/ Δ V maximum; Perhaps adopt pH～V figure method, the volume of the vs that consumes when trying to achieve titration end-point according to the method for doing the curve tangent line.
For the system of above-mentioned difficult employing developer, although V～Δ pH/ Δ V method most cases can prove effective, the peaked situation of two or more Δ pH/ Δ V appears sometimes, promptly its maximal value is more than one, so just can't determine the terminal point of titration; For adopting pH～V figure method, manual plotting is very loaded down with trivial details, does also and can produce sizable error.Although, all have certain defective so these two kinds of methods can solve many problems.Potential of hydrogen when especially analysis has the hydrolysis ion to exist or the concentration of weak acid and weak base, error is bigger.
Technical scheme
The present invention will be at V～Δ pH/ Δ V method, the pH～existing problem of V figure method analytical solution acid base concentration, provide a kind of simple to operate, measure the analytical approach of acid base concentration accurately.
The principle of acid base titration is exactly that acid-base titration curve slope maximum is equivalent point, this on mathematics corresponding be exactly the function second derivative be zero point.According to present principles, technical scheme provided by the present invention is: the concentration of coming titration alkali/acid solution to be measured with the acid/alkali of concentration known, end to titration from titration is initial, the consumption x of the acid/aqueous slkali of the pH value of mixed solution and concentration known comes match pH-x titration curve pH=ax with cubic function when writing down each titration according to this
3+ bx
2+ cx+z, getting its second derivative then and making it is zero, promptly
The volume that acid/aqueous slkali consumed of concentration known during for titration end-point according to this volume, calculates the concentration of alkali/acid solution to be measured.
For the cubic function curve that makes match more can react titration process, be titrated near the flex point, sampling spot is intensive as far as possible.
This method has prevented that the generation of a plurality of maximal value situations from appearring in V～Δ pH/ Δ V method, because its maximal value is unique; In addition, this titration jump part method of all using of has have a few also been avoided effectively drops to minimum owing to put individually and the error that deviation causes occurs with error; Simultaneously, this method directly adopts the matched curve of excel software, automatically obtain the fit equation of required pH-x titration curve, the concentration of free soda acid or the concentration of weak acid and weak base can be easy be analyzed when having the hydrolysis ion to exist in the solution in mapping, so this method not by hand exactly.
Description of drawings
Fig. 1 be embodiment 1 measured the pH-x titration curve;
Fig. 2 be embodiment 2 measured pH-x titration curve 1;
Fig. 3 be embodiment 2 measured pH-x titration curve 2;
Fig. 4 be embodiment 2 measured pH-x titration curve 3;
Fig. 5 be embodiment 2 measured pH-x titration curve 4;
Embodiment
Below in conjunction with two specific embodiments, technical scheme provided by the present invention is further explained.
The concentration analysis of free nitric acid under the situation that a large amount of aluminium nitrates exist.Owing to contain the stronger aluminium ion of hydrolysis, therefore directly the acid base titration indicator method cannot carry out concentration analysis to the free nitric acid in the system in this system.Just can address this problem well and adopt cubic function fitting process provided by the present invention.Come the Al (NO of the unknown concentration of titration 2ml with the NaOH solution of 1mol/L
3)
3The concentration of solution ends to titration from titration is initial, and the pH value of mixed solution and the consumption of NaOH solution are pH=-1.5077x with excel software match pH-x titration curve when writing down each titration according to this
3+ 54.718x
2-660.42x+2653.8, getting its second derivative then and making it is zero, then
The volume of NaOH solution consumption when promptly being titration end-point, the principle of acid base equilibrium during again according to titration end-point, the concentration that calculates aluminum nitrate solution is 2.02mol/L.
With excel software match pH-x titration curve the time, R
2=0.9983, show that the accordance of the curve that simulates in the present embodiment is very good.This method has successfully been used the concentration analysis of nitric acid in rare TBP extraction process 1AF, the 1AW sample.
Dimethyl hydroxylamine is to be used for reductive agent and the holding reductant that nuclear fuel aftertreatment technology uranium plutonium separates, and the concentration of accurately analyzing them has very important meaning to the research technological process.What present concentration analysis to dimethyl hydroxylamine generally adopted is with the salt acidometric titration, and methyl red is the method for indicator colour developing.The shortcoming of this method is that the developer variable color is not obvious, is not easy to judge titration end-point, but utilizes method provided by the present invention then can address this problem well.Shown in accompanying drawing 2～5, with the operation steps that embodiment 1 is provided, four dimethyl hydroxylamine parallel sample are used 0.1001ml salt acidometric titration respectively, with excel software match pH-x titration curve, the volume of four hydrochloric acid that parallel sample consumes of calculating is respectively:
V
HCl 1＝20.865/0.6814/3＝10.21ml
V
HCl 2＝16.222/0.5113/3＝10.58ml
V
HCl 3＝18.044/3/0.5864＝10.26ml
V
HCl 4＝32.57/3/1.0518＝10.32ml
Be averaged four, draw the volume 10.34ml that titration 1ml dimethyl hydroxylamine consumes 0.1001ml hydrochloric acid, then the concentration of dimethyl hydroxylamine is 1.035mol/L.
Utilize computer software to realize provided by the inventionly measuring the method for unknown solution potential of hydrogen, also should be subjected in the scope of protection of present invention by match pH-x cubic function titration curve.
Claims (4)
1. acidity and alkalinity analysis method, come the concentration of titration alkali/acid solution to be measured with the acid/alkali of concentration known, end to titration from titration is initial, the consumption x of the acid/aqueous slkali of the pH value of mixed solution and concentration known when writing down each titration according to this, utilize the principle of acid base equilibrium to calculate the concentration of alkali/acid solution to be measured in titration end-point, it is characterized in that: with cubic function match pH-x titration curve pH=ax
3+ bx
2+ cx+z, getting its second derivative then and making it is zero, then
The volume that acid/aqueous slkali consumed of concentration known when promptly being titration end-point according to this volume, calculates the concentration of alkali/acid solution to be measured.
2. acidity and alkalinity analysis method according to claim 1 is characterized in that: be titrated near the flex point, sampling spot is intensive as far as possible.
3. acidity and alkalinity analysis method according to claim 1 is characterized in that: with excel software match pH-x titration curve.
4. acidity and alkalinity analysis method according to claim 1 is characterized in that: use plural parallel sample, getting its mean value that consumes volume is the consumption of known solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510135529 CN1804617A (en) | 2005-12-30 | 2005-12-30 | Method for analyzing pH value |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510135529 CN1804617A (en) | 2005-12-30 | 2005-12-30 | Method for analyzing pH value |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1804617A true CN1804617A (en) | 2006-07-19 |
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ID=36866707
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|---|---|---|---|
| CN 200510135529 Pending CN1804617A (en) | 2005-12-30 | 2005-12-30 | Method for analyzing pH value |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680555A (en) * | 2012-03-31 | 2012-09-19 | 武汉钢铁(集团)公司 | Method for measuring free acid concentration in acid liquid |
| CN106353460A (en) * | 2016-09-18 | 2017-01-25 | 国网福建省电力有限公司 | Device and method for intelligently and quickly measuring acid values of main transformer insulation paper |
| CN109668941A (en) * | 2018-12-06 | 2019-04-23 | 普瑞斯伊诺康有限公司 | A kind of method of sulfuric acid and manganese sulfate concentration in measurement electrolyte aqueous solution |
| CN110687062A (en) * | 2019-09-30 | 2020-01-14 | 李朋 | Detection system and detection method for sulfur trioxide content in flue gas |
| CN112881588A (en) * | 2021-01-18 | 2021-06-01 | 大庆油田有限责任公司 | Method for measuring hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement |
-
2005
- 2005-12-30 CN CN 200510135529 patent/CN1804617A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680555A (en) * | 2012-03-31 | 2012-09-19 | 武汉钢铁(集团)公司 | Method for measuring free acid concentration in acid liquid |
| CN106353460A (en) * | 2016-09-18 | 2017-01-25 | 国网福建省电力有限公司 | Device and method for intelligently and quickly measuring acid values of main transformer insulation paper |
| CN106353460B (en) * | 2016-09-18 | 2018-12-11 | 国网福建省电力有限公司 | Acid value intelligence rapid determination device and method in a kind of main change insulated paper |
| CN109668941A (en) * | 2018-12-06 | 2019-04-23 | 普瑞斯伊诺康有限公司 | A kind of method of sulfuric acid and manganese sulfate concentration in measurement electrolyte aqueous solution |
| CN109668941B (en) * | 2018-12-06 | 2021-08-03 | 普瑞斯矿业(中国)有限公司 | Method for measuring concentrations of sulfuric acid and manganese sulfate in electrolyte aqueous solution |
| CN110687062A (en) * | 2019-09-30 | 2020-01-14 | 李朋 | Detection system and detection method for sulfur trioxide content in flue gas |
| CN112881588A (en) * | 2021-01-18 | 2021-06-01 | 大庆油田有限责任公司 | Method for measuring hydrolysis degree of partially hydrolyzed polyacrylamide for oil displacement |
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