Phenolphthalein endpoint

One 1-ml aliquot is added to 1.0 ml of freshly-distilled 1,2-dibromo-ethane (bp 132°C) in an oven-dried flask which contains a static atmosphere of nitrogen or argon. After the resulting solution has been allowed to stand at 25°C for 5 min, it Is diluted with 10 rat of water and titrated for base content (residual base) to a phenolphthalein endpoint with standard 0.100 M hydrochloric acid. The second 1-mL aliquot is added cautiously to 10 ml of water and then titrated for base content (total base) to a phenol phthalein endpoint with standard aqueous 0.100 M hydrochloric acid. The methyllithium concentration is the difference between the total base and residual base concentrations.2 Alternatively, the methynithiura concentration may be determined by titration with a standard solution of sec-butyl alcohol employing 2,2 -bipyridyl as an indicator. 

Alkalinity and Lime Content. Alkalinity is the ability of a solution or mixture to react with an acid. The phenolphthalein alkalinity refers to the amount of acid required to reduce the pH to 8.3, the phenolphthalein endpoint. The phenolphthalein alkalinity of the mud and mud filtrate is called the and Pp respectively. The P. test includes the effect of only dissolved bases and salts while the P test includes the effect of both dissolved and suspended bases and salts. The methyl orange alkalinity refers to the amount of acid required to reduce the pH to 4.3, the methyl orange endpoint. The methyl orange alkalinity of the mud and mud filtrate is called the and Mp respectively. The API diagnostic tests include the determination of P, Pp and Mp All values are reported in cubic centimeters of 0.02 N (normality = 0.02) sulfuric acid per cubic centimeter of sample. 

Analytical. It can be titrated with std base to a salmon colored phenolphthalein endpoint and can be quanty pptd from aq solns with tetraphenylarsonium chloride KSp of the complex in w is 6.9 x 10 9 (Ref 22). This procedure can be adapted to the analysis of compds, such as bis-(trinitroethyl) urea, which regenerate... 

Alkalinity measurement is also required for the determination of active matter by difference and equivalent weight calculations. It can be determined as two of the following compounds sodium bicarbonate, sodium carbonate, or sodium hydroxide. The sample is titrated to a phenolphthalein endpoint to determine the sodium hydroxide/sodium carbonate content. An added measure of acid converts any bicarbonate to carbon dioxide, which is subsequently removed from the solution. Back-titration of the excess acid gives a measure of the amount of bicarbonate and/or carbonate present. 

Most water analysis results are rather easily interpreted. However, two simple and useful tests need explanation. These are the P and M alkalinity. The water is titrated with N/30 HC1 to the phenolphthalein endpoint at pH 8.3. This is called the P alkalinity. Similar titration to the methyl orange end point at pH 4.3 is called the M alkalinity. They are reported as ppm CaC03. 

Calculations The total volume of 1 N sulphuric acid consumed in the titration was required to neutralize NaOH and Na Oj, thereby converting the latter first to NaHC03 at the phenolphthalein endpoint and then to H2C03 at the methyl orange end-point. 

Benzoic acid is assayed by titration with 0.1 N sodium hydroxide VS to a pink phenolphthalein endpoint. The procedure calls for the dissolution of about 500 mg of accurately weighed sample in 25 mL of diluted alcohol (previously neutralized with 0.1 N sodium hydroxide). Each milliliter of 0.1 N sodium hydroxide is equivalent to 12.21 mg of benzoic acid. 

The buffering capacity of milk is often estimated by determining its titratable acidity, which involves titrating a sample of milk, containing a suitable indicator (usually phenolphthalein), with NaOH and thus is a measure of the buffering capacity of the milk between its natural pH and the phenolphthalein endpoint (i.e. between about pH 6.6 and 8.3). Titratable acidity is normally used to estimate the freshness of milk and to monitor the production of lactic acid during fermentation. Fresh milk typically requires 1.3-2.0 milliequivalents OH to titrate 100ml from pH 6.6 to pH 8.3 (13-20 ml of 0.1 M NaOH), i.e. fresh milk has a titratable acidity of 0.14 to 0.16%, expressed as lactic acid. 

The apparent acid strength of boric acid is increased both by strong electrolytes that modify the structure and activity of the solvent water and by reagents that form complexes with B(OH) 4 and/or polyborate anions. More than one mechanism may be operative when salts of metal ions are involved. In the presence of excess calcium chloride the strength of boric acid becomes comparable to that of carboxylic acids, and such solutions may be titrated using strong base to a sharp phenolphthalein endpoint. Normally titrations of boric acid are carried out following addition of mannitol or sorbitol, which form stable chelate complexes with B(OH) 4 in a manner typical of polyhydroxy compounds. Equilibria of the type ... 

Fractionation of milk and titration of the fractions have been of considerable value. Rice and Markley (1924) made an attempt to assign contributions of the various milk components to titratable acidity. One scheme utilizes oxalate to precipitate calcium and rennet to remove the calcium caseinate phosphate micelles (Horst 1947 Ling 1936 Pyne and Ryan 1950). As formulated by Ling, the scheme involves titrations of milk, oxalated milk, rennet whey, and oxalated rennet whey to the phenolphthalein endpoint. From such titrations, Ling calculated that the caseinate contributed about 0.8 mEq of the total titer of 2.2 mEq/100 ml (0.19% lactic acid) in certain milks that he analyzed. These data are consistent with calculations based on the concentrations of phosphate and proteins present (Walstra and Jenness 1984). The casein, serum proteins, colloidal inorganic phosphorus, and dissolved inorganic phosphorus were accounted for by van der Have et al (1979) in their equation relating the titratable acidity of individual cow s milks to the composition. The casein and phosphates account for the major part of the titratable acidity of fresh milk. 

A 366 mg sample of a compound A, a corrosive volatile red liquid, is dissolved in water. The solution is distinctly acidic but cannot be titrated with NaOH because the orange color interferes with detection of the endpoint. However, the solution is titrated with standard Ba(OH) 2 solution, requiring 6 millimoles of the latter to reach the phenolphthalein endpoint. At the end of the titration, a precipitate, B. remains. 

Note The water used for sample dispersion should require not more than 0.05 mL of 0.1 N acid or alkali per 200 mL of sample to obtain the methyl red or phenolphthalein endpoint, respectively. 

Procedure Transfer 25.0 mL of the Substrate Solution to a 32- x 200-mm test tube. To a second 32- x 200-mm test tube transfer 25.0 mL of the Chloride-Acetate Buffer Solution (blank). Equilibrate both tubes in a 35° 0.1° water bath for 20 min. Add 3.0 mL of the Sample Preparation to each test tube, mix, and insert a glass sparger into each tube with a preadjusted air flow of 700 to 750 mL/min. If excessive foaming occurs, add 3 drops of the Octadecanol Solution to each tube. After exactly 15 min, remove the sparge and rinse any adhering reaction mixture back into the tube with water. Immediately add 10 mL of the Sodium Hydroxide Solution and 3 drops of the Phenolphthalein Solution to each tube. Insert a small magnetic stirrer bar, stir, and titrate to the phenolphthalein endpoint with the standardized 0.05 N Hydrochloric Acid Solution. 

Procedure Into a series of four, 100-mL volumetric flasks, transfer 5, 7, 10 and 15 mL respectively of the stock solution. Into a 100-mL volumetric labelled blank, pipet 10 mL of 0.1 N NaOH-MeOH solution. To all add 2 drops of 0.1% ethanolic phenolphthalein indicator solution, and 20 mL of aqueous 1.5% sodium sulfate (Na2S04). Acidify each, in turn, to the phenolphthalein endpoint with 1 N hydrochloric acid and immediately add 25 mL of 1 M ferric ammonium sulfate (Fe(NH4)(S04)2l solution. Dilute to the mark with 1.5% Na2SC 4. Let stand 10 min, then read absorbance at 458 nm. Plot absorbance vs. concentration. 

Plpet 5 mL of the hexane solution containing 4-dodecylbenzenesulfonyl azides into a 100-mL volumetric flask and dilute to the mark with methanol. Pipet 5 mL of this solution Into a small stoppered flask. Add 2 mL of aqueous t N potassium hydroxide solution and heat at 75°C for 20 min. Allow to cool to room temperature, add 2 drops of 0.1% phenolphthalein solution, and 10 mL of 1.5% Na2S04. Shake, then transfer quantitatively to a 60-mL separatory funnel. Add 10 mL of butanol (or isoamyl alcohol) to the sample flask, shake, then transfer to the separatory funnel. Shake the funnel, let the layers separate, then remove the bottom (H2O) layer into a 100-mL volumetric flask, Add an additional 10 mL of 1.5% Na2SC>4 to the alcohol layer in the separatory funnel, shake, let the layers separate, then transfer the water layer to the volumetric flask. Neutralize the lined water layers to the phenolphthalein endpoint with 1 N hydrochloric acid, then immediately add 25 mL of Fe(NH4)(S04>2. Dilute to the mark with 1.5% Na2S04 solution, let stand 10 min, then read absorbance at 458 nm. Read azide concentration against the NaN3 calibration curve. 

Titration. The wet pdymer crumb (- 1 g) was added to a tared 250 ml erlenmeyer flask and dissolved in 75 ml of THF. The sample was then titrated with ethandlic KOH (0.05 N) to a phenolphthalein endpoint. Removal of the solvents was then accomplished by passing a stream of nitrogen over the solution, followed by drying in-vacuo at 70°C until constant weight was reached. The original dry weiffot of the polymer sample was then calculated and the percent sulfonation obtained. 

The reaction flasks (50 ml Erlenmeyer) were dry, argon-filled, and capped with serum stoppers. To each was added 10 ml THF and 1 ml benzyl chloride. Four ml of catalyst solution were added to two of these and 8 ml to two more. After at least one minute, the solutions were poured into distilled water (100 ml), and the LiOH was titrated with standard acid to a phenolphthalein endpoint. The difference between the 4 ml and 8 ml aliquot samples is the inactive content of the catalyst solution. This takes into account any impurities which may have been present in the THF or benzyl chloride. Total lithium content was determined by quenching 4 ml of the catalyst solution in 100 ml of water and titrating with standard acid. The molarity of the catalyst solution in active butyllithium is simply the total LiOH acid titre less the inactive LiOH titre. 

A student carries out an experiment to standardize (determine the exact concentration of) a sodium hydroxide solution. To do this, the student weighs out a 1.3009-g sample of potassium hydrogen phthalate (KFIC8FI4O4, often abbreviated KHP). KFIP (molar mass 204.22 g/mol) has one acidic hydrogen. The student dissolves the KHP in distilled water, adds phenolphthalein as an indicator, and titrates the resulting solution with the sodium hydroxide solution to the phenolphthalein endpoint. The difference between the final and initial buret... 

A sample of water from the overflow of the recarbonation basin that follows a precxpitation/softening process has a pH of 9.0 200 ml of the water require 1.1 ml of 0,02 N H2S04 to titrate it to the phenolphthalein endpoint and 22.3 ml of 0.02 N H2SO4 to titrate it further to the methyl orange endpoint. Assuming the sample contains no calcite particles, what are the total and carbonate alkalinities of the sample in meq/liter and the total alkalinity in mg/liter as CaCOa ... 

Carbonate alkalinity the meq of acid/liter of sample required to reach the phenolphthalein endpoint = 1.1 ml X 0.02 eq/liter x 1000 meq/eq x 1/(200 ml sample volume)... 

An acid form of a cation exchange resin, H(exchanger), can be used in place of the sodium form described in part E. Hydrogen ions, H+, are then displaced by the +2 cations. Suppose that 25.00 mL of permanently hard water are eluted through an acid cation exchange resin followed by washing of the resin. The eluent then requires 11.26 mL of 0.1038 M sodium hydroxide, NaOH, solution for titration to a phenolphthalein endpoint. 

For routine analysis a measurement of titratable acidity is usually sufficient, with the acidity of the fruit/fruit product calculated as the predominant acid, e.g., as citric acid in citrus fruits, as malic acid in apples. The sample is diluted in distilled water and titrated against dilute sodium hydroxide to either a phenolphthalein endpoint or to pH 8.10. Volatile acidity, generally expressed as acetic acid, can be measured by distilling the sample using a steam distillation apparatus, with titration of the distillate as above. Individual acids can be determined using a... 

At regular intervals, use the volumetric pipet to remove a 10-mL aliquot from the reaction mixture, and quench the reaction by adding the aliquot to 10 ml of 98% 2-propanol contained in the 125-mL Erlenmeyer flask. Be sure to note the time of addition of the aliquot, probably best taken as the time at which one-half of it has been added. Titrate the solution with base to the phenolphthalein endpoint just as you did in the blank determination. 

Weigh accurately a 200-milligram sample of dialdehyde cotton gauze and place it in a 125 mL Erlenmeyer flask. To the flask is add 10 mL of standardized 0.1 N sodium hydroxide and the flask is swirled and placed in a 70 C water bath for 60 minutes. The flask is cooled under running tap water. The residual sodium hydroxide is then titrated with standardized 0.1 N hydrochloric acid to the phenolphthalein endpoint. The percent dicarbonyl units is calculated with the following equation ... 

P alkalinity Phenolphthalein alkalinity of a water as determined by titration with standard acid solution to the phenolphthalein endpoint (pH approximately 8.3). It includes both carbonate and hydroxide alkalinity. 

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