Water solutions, titrations

To determine the exact diazomethane content, allow an aliquot portion of the ethereal diazomethane solution to react with an accurately weighed amount (say, about 1 g.) of A. R. benzoic acid in 60 ml. of anhydrous ether. The solution should be completely decolourised, thus showing that the benzoic acid is present in excess. Dilute the solution with water and titrate the excess of benzoic acid with standard 0 IN alkali using phenolphthalein as indicator. 

Methanol is included to prevent the further reaction of py SO3 with water. The titration s end point is signaled when the solution changes from the yellow color of the products to the brown color of the Karl Fischer reagent. 

This experiment describes a method for determining the acidity, reported as an equivalent molarity of H2SO4, of rain water. Because the volume of standard base needed to titrate a sample of rain water is small, the analysis is done by a standard addition. A 10.00-mL sample of nominally 0.005 M H2SO4 is diluted with 100.0 mL of distilled water and standardized by titrating with 0.0100 M NaOH. A second 10.00-mL sample of the sulfuric acid is mixed with 100.0 mL of rain water and titrated with the same solution of NaOH. The difference between the two equivalence point volumes... 

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. 

Calcium Chloride [25]. Calcium chloride estimation is based on calcium titration. To 20 ml of 1 1 mixture of toluene (xylene) isopropyl alcohol, add a 1-ml (or 0.1-ml, if calcium is high) sample of oil-base mud, while stirring. Dilute the mixture with 75 to 100 ml of distilled water. Add 2 ml of hardness buffer solution and 10 to 15 drops of hardness indicator solution. Titrate mixture with standard versenate solution until the color changes from wine-red to blue. If common standard versenate solution (1 ml = 20 g calcium ions) is used, then... 

The experimental setup for a titration is shown in Figure 4.7. The flask contains vinegar, a water solution of a weak organic add called acetic acid. A solution of sodium hydroxide of known concentration is added from a buret. The net ionic equation for the acid-base reaction that occurs is... 

A solution consisting of25.00 g NH4C1 in 178 mL of water is titrated with 0.114 AfKOH. 

Analyses, (a) Original zinc-ion solution. Dilute 2.00 mL (pipette) to 100 mL in a graduated flask. Pipette 10.0 mL of the diluted solution into a 250 mL conical flask, add ca 90 mL of water, 2 mL of the buffer solution, and sufficient of the solochrome black indicator mixture to impart a pronounced red colour to the solution. Titrate with standard 0.01 M EDTA to a pure blue colour (see Section 10.59). 

Pipette 25 mL of the copper solution (0.01 M) into a conical flask, add 100 mL de-ionised water, 5 mL concentrated ammonia solution and 5 drops of the indicator solution. Titrate with standard EDTA solution (0.01 M) until the colour changes from purple to dark green. 

Pipette 25 mL nickel solution (0.01 M) into a conical flask and dilute to 100mL with de-ionised water. Add the solid indicator mixture (50mg) and 10 mL of the 1M ammonium chloride solution, and then add concentrated ammonia solution dropwise until the pH is about 7 as shown by the yellow colour of the solution. Titrate with standard (0.01 M) EDTA solution until the end point is approached, then render the solution strongly alkaline by the addition of 10 mL of concentrated ammonia solution, and continue the titration until the colour changes from yellow to violet. The pH of the final solution must be 10 at lower pH values an orange-yellow colour develops and more ammonia solution must be added until the colour is clear yellow. Nickel complexes rather slowly with EDTA, and consequently the EDTA solution must be added dropwise near the end point. 

Pipette 25 mL of the solution to be analysed into a 250 mL conical flask and dilute to 100 mL with de-ionised water the original solution should be about 0.02M with respect to calcium and may contain barium to a concentration of up to 0.2M. Add 10 mL sodium hydroxide solution (1M) and check that the pH of the solution lies between 11 and 12 then add three drops of the indicator solution. Titrate with the standard CDTA solution until the pink colour changes to blue. 

Procedure. Place 10 mL of the solution containing the two metals (the concentration of neither of which should exceed 0.01 M) in a 600mL beaker fitted with a magnetic stirrer, and dilute to 100 mL with de-ionised water. Add 20 mL of standard (approx. 0.01 M) EDTA solution and add hexamine to adjust the pH to 5-6. Then add a few drops of the indicator solution (0.5 g xylenol orange dissolved in 100 mL of water) and titrate the excess EDTA with a standard lead nitrate solution (0.01 M), i.e. to the formation of a red-violet colour. 

Procedure. Dissolve a weighed amount of ferro-manganese (about 0.40 g) in concentrated nitric acid and then add concentrated hydrochloric acid (or use a mixture of the two concentrated acids) prolonged boiling may be necessary. Evaporate to a small volume on a water bath. Dilute with water and filter directly into a 100 mL graduated flask, wash with distilled water and finally dilute to the mark. Pipette 25.0 mL of the solution into a 500 mL conical flask, add 5 mL of 10 per cent aqueous hydroxylammonium chloride solution, 10 mL of 20 per cent aqueous triethanolamine solution, 10-35 mL of concentrated ammonia solution, about 100 mL of water, and 6 drops of thymolphthalexone indicator solution. Titrate with standard 0.05M EDTA until the colour changes from blue to colourless (or a very pale pink). 

Pipette 25.0 mL of the potassium ion solution (about 10 mg K + ) into a 50 mL graduated flask, add 0.5 mL 1M nitric acid and mix. Introduce 20.0 mL of the sodium tetraphenylborate solution, dilute to the mark, mix, then pour the mixture into a 150mL flask provided with a ground stopper. Shake the stoppered flask for 5 minutes on a mechanical shaker to coagulate the precipitate, then filter most of the solution through a dry Whatman No. 40 filter paper into a dry beaker. Transfer 25.0 mL of the filtrate into a 250 mL conical flask and add 75 mL of water, 1.0 mL of iron(III) nitrate solution, and 1.0 mL of sodium thiocyanate solution. Titrate with the mercury(II) nitrate solution as described above. 

If it is desired to base the standardisation directly upon arsenic(III) oxide, proceed as follows. Weigh out accurately about 0.20 g of pure arsenic(III) oxide into a conical flask, dissolve it in 10 mL of 1M sodium hydroxide, and add a small excess of dilute sulphuric acid (say, 12-15 mL of 0.5M acid). Mix thoroughly and cautiously. Then add carefully a solution of 2 g of sodium hydrogencarbonate in 50 mL of water, followed by 2 mL of starch solution. Titrate slowly with the iodine solution to the first blue colour. Repeat with two other similar quantities of the oxide. 

C) With a standard solution of iodine. If a standard solution of iodine is available (see Section 10.112), this may be used to standardise the thiosulphate solution. Measure a 25.0 mL portion of the standard iodine solution into a 250 mL conical flask, add about 150 mL distilled water and titrate with the thiosulphate solution, adding 2 mL of starch solution when the liquid is pale yellow in colour. 

Griffin and Albaugh [102] describe a procedure whereby the neutral AOS product is converted to the parent acids by cation exchange and then titrated potentiometrically. A dilute aqueous solution of AOS is passed through cationic ion exchange resin in acid form. The acids are eluted with small portions of water and titrated potentiometrically using tetrabutylammonium hydroxide solution in a solvent mixture of 70 30 benzene/methanol. It is probable that the benzene can be replaced with toluene for safety reasons or that ASTM titration solvent (ASTM D664 toluene/propan-2-ol/water) can be used. 

N-Bromosuccinimide purchased from Arapahoe Chemical Company was used without purification. If the purity of the N-bromosuccinimide is in doubt, it should be titrated before use by the standard iodide-thiosulfate method and purified, if necessary, by recrystallization from 10 times its weight of water. Solutions of N-bromosuccinimide in dimethyl sulfoxide cannot be stored, since the solvent is oxidized by the brominating reagent. 

C04-0030. The acidic component of vinegar is acetic acid. When 5.00 mL of vinegar was added to water and the solution titrated with the 0.1250 M NaOH, it took 33.8 mL to reach the stoichiometric point. Calculate the molarity of acetic acid in vinegar. 

C18-0103. When a solution of leucine (an amino acid) in water is titrated with strong base, the pH before titration is 1.85, the pH at the midpoint of the titration is 2.36, and the pH at the stoichiometric point is 6.00. Determine the value of K. for leucine. 

Furthermore, pH electrode calibration can be performed in situ by the new method [48], concurrently with the pKj determination. This is a substantial improvement in comparison to the traditional procedure of first doing a blank titration to determine the four Avdeef-Bucher parameters [24]. The traditional cosolvent methods used with sparingly soluble molecules can be considerably limited in the pH<4 region when DMSO-water solutions are used. This is no longer a serious problem, and routine blank titrations are now rarely needed in the new in situ procedure. 

The anticancer agent Methotrexate (MTX) was conjugated with LDH by a coprecipitation method. To synthesize the MTX-LDH conjugate, powdered MTX was dissolved in decarbonated water, and titrated with NaOH (0.5 M) solution to give a 0.043 M solution of MTX at pH 7. The mixed metal solution of Mg(N03)2-6H20 and A1 (N03)3-9H20 with molar ratio Mg/Al = 2/1 was added to the MTX solution and the solution was titrated with NaOH solution until pH 9.5 to produce yellowish precipitates [7,26]. 

If desired, the cyclopentadienylsodium concentration in solution can be determined by withdrawing 1 ml. of solution, diluting this with 100 ml. of water, and titrating the resulting aqueous sodium hydroxide solution with 0.11V hydrochloric acid using methyl red as an indicator. 

Standardization. A JR. sodium fluoride (25 mg.) was dissolved in water and the solution titrated with thorium nitrate. 

Procedure Weigh accurately about 0.3 g of ferrous fumarate and dissolve in 15 ml of dilute sulphuric acid by the help of gentle heating. Cool, add 50 ml of water and titrate immediately with 0.1 N ammonium ceric sulphate, employing ferroin sulphate solution as indicator. Each ml of 0.1 N ammonium ceric sulphate is equivalent to 0.01699 g of C4H2Fe04. 

Procedure Weigh accurately about 0.5 g of ferric ammonium citrate and dissolve the sample in 15 ml DW. Add to it slowly 1 ml of sulphuric acid and warm gently to attain a yellow colouration so as to decompose the iron and ammonium citrate complex completely. Cool and add 0.1 N potassium permanganate solution dropwise from a burette to obtain a pink colour that persists for 5 seconds. To the resulting solution add hydrochloric acid 15 ml and potassium iodide 2.0 g, shake well and set aside for 3 minutes so that iodine may be liberated completely. Now, add 60 ml of water and titrate with 0.1 N sodium thiosulphate solution while shaking the contents continuously till a colourless end-point is achieved. 

Standardization of 0.1 M Ethanolic Sodium Hydroxide Solution Vs Dissolve 0.2 g of benzoic acid in a mixture of 10 ml of ethanol (96%) and 2 ml of water and titrate with the ethanolic sodium hydroxide solution using 0.2 ml of thymolphthalein solution (a 0.1 % w/v solution of thymolphthalein in ethanol (96%) as indicator. Each ml of 0.1 M ethanolic sodium hydroxide Vs is equivalent to 12.21 mg of C7H602. 

Figure 4.3 Potentiometric titration curve obtained by dissolving 200 mg of dishwashing fluid in water and titrating against hexadecylpyridinium chloride solution, employing a zeolite-polydimethylsiloxane (NaY-PDMS) modified electrode (cf. SAQ 4.3). From Matysik, S Matysik, F.-M., Mattusch, J. and Einicke, W.-D., Electroanalysis, 10, 98-102, (1998), Wiley-VCH, 1998. Reproduced by permission of Wiley-VCH.

Figure G.l shows the titration curve NgQi) and the BI [plotted as 2 - 20(h)], with h = [H] for a - a -di-tert-butyl succinic acid in 50% ethanol-water solution. Note that the locations of the two peaks of the derivatives of these curves are nearly identical for the two curves.

Karl Fischer reagent analy chem A solution of 8 moles pyridine to 2 moles sulfur dioxide, with the addition of about 15 moles methanol and then 1 mole iodine used to determine trace quantities of water by titration. karl fish-or re a-jont Karl Fischer technique analy chem A method of determining trace quantities of water by titration the Karl Fischer reagent is added in small increments to a glass flask containing the sample until the color changes from yellow to brown or a change in potential is observed at the end point. karl fish-or tek nek kauri-butanol value analychem The measure of milliliters of paint or varnish petroleum thinner needed to cause cloudiness in a solution of kauri gum in butyl alcohol. kail-re byut-3n,ol, val-yu ... 

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