Alkaline mixed indicator

By performing the titration in acid and alkaline solution or before and after acid or alkaline hydrolysis it is possible to analyse some two- and three-component surfactant mixtures without prior separation. This is described in chapter 8. An alkaline mixed indicator is required for some... 

Transfer 150 ml of the silver nitrate reagent to each of two 250-ml glass-stoppered Erlenmeyer flasks. Place the flasks in a suitable ice bath until, die temperature of the contents Is 32°to 39.2 F (0° to 4°C). Add 7 to 9 drops of the mixed indicator to each flask and, if necessary, neutralize to a gray-green color with 0.02N sodium hydroxide if. acid or with 0.02N nitric acid if alkaline. Reserve one of the flasks for the blank and into the second flask pour 0 ml of propellant. Compare the color of the sample with that of the blank. A purple color in the sample solution indicates... 

NH4 is distilled after alkalinization. Titration with standardized 0.01 M H2S04 and a mixed indicator (methylene blue and methylene red) NHJ is distilled from water after alkalinization. Ammonium reacts with Nessler s reagent (I2Hg—2IK) to form a yellow-brown colored complex (410—425 nm)... 

Alkalinity co - I ICO, Acid-base titration Titrating with standardized 0.01 M H2S04 using phenolphthalein as indicator until the pink color disappears at about pH 8.3 titration of the same sample is then continued until the end point is reached at pH 4.5 using a bromocresol green-methyl red mixed indicator (total alkalinity) Applicable to natural and waste water. Concentrations of bicarbonate, carbonate, and hydroxide can be calculated. The titration end points can be measured potentiometrically 50,51,67-69... 

A cold process with solid caustic soda or austic potash allows an accurate approach at home. The following parts by weight can be used for 10 parts solid austic soda, or 14 parts austic potash, dissolved in 20 parts hot water 72 parts beef tallow OR 73 parts lard OR 75 parts olive oil OR 71 parts palm oil. Gendy melt the fat, if solid. The two liquids are best mixed at around 40 C, mixing too warm or at uneven tempertures are common errors. Pour the fat then the caustic soda into a suitable vessel and stir or shake vigorously. Mixed well the two liquids should not separate, if they do they must be reshaken or stirred. After a week the soap can be tested to see if it produces suds. Test for excess alkalinity with indicator paper. 

The distillation method [13-15] is based on the separation of ammonia from the sample by distillation from an alkaline medium, followed by volumetric or photometric determination of ammonia in the distillate. In the case of volumetric determination the separated ammonia trapped in a receiver with boric acid in the form of NH4H2BO3 is titrated against standard H2SO4 using a mixed indicator (Methyl Red and Methylene Blue)... 

AFS standard specimens prepared in this manner were strong enough to be handled and in this case they had a pink color due to the phenolphthalein indicator added to the alkaline mix. 

The colorimetric Nesslerization method uses alkaline phenol and hypochlorite to react with ammonia to form indophenol blue in an amount proportional to the ammonia concentration. The blue color is intensified with sodium nitroprusside, and the concentration is measured using a calibrated colorimeter. The titration of basic ammonia is accomplished with standard sulfuric acid using a mixed indicator. Determination of ammonia may also be based upon the indophenol reaction adapted to automated gas-segmented continuous flow analysis. Potentiometric determination of ammonia is performed by ion-selective ammonia electrodes. 

The classification is done by adding 1 ml of the mixed indicator (disulphine blue V and dimidium bromide) to two small portions of a solution of the surfactant, one acid and the other alkaline, adding a few... 

Titrate two 25 ml portions with 0.004 M benzethonium chloride, one portion using acid mixed indicator and the other using bromophenol blue in alkaline solution. 

B. Titration with benzethonium chloride in alkaline solution. The solution must be at least 0.1 M in hydroxide ion. Potentiometric titration is preferred, and the bromophenol blue method is probably better than the mixed indicator procedure. The present author s limited experience suggests that WW amphoterics are titrated rather more successfully as cationics than as anionics. 

Sodium bicarbonate is generally added to increase alkalinity and muriatic acid (HCl) or sodium bisulfate (NaHSO ) to reduce it. In general, with acidic sanitizers such as chlorine gas or trichloroisocyanuric acid, ideal total alkalinity should be in the 100—120 ppm range, whereas, with alkaline products such as calcium, lithium, or sodium hypochlorite, a lower ideal total alkalinity of 80—100 ppm is recommended (14). Alkalinity is deterrnined by titration with standard sulfuric acid using a mixed bromcresol green—methyl red indicator after dechlorination of the sample with thiosulfate. Dechlorination with thiosulfate causes higher readings due to formation of hydroxyl ion (32) ... 

The dyestuff is thoroughly mixed with 100 times its weight of sodium sulphate, and 1 g of the mixture is used in each titration. The indicator is not very stable in alkaline solution. 

Alkalinity. To 25ml of w, add 1 drop of 0.1% methyl red indicator soln (60% ale) and 0.0 IN acid or base until the soln is just pink. Add 25ml of specimen, mix well, then titrate with 0.01N sulfuric acid until the pink color is restored. Calc the % NH3 by wt as follows ... 

Various workers have discussed the determination of total alkalinity and carbonate [ 10-12], and the carbonate bicarbonate ratio [ 12] in seawater. A typical method utilises an autoanalyser. Total alkalinity (T milliequivelents per litre) is found by adding a known (excess) amount of hydrochloric acid and back titrating with sodium hydroxide solution a pH meter records directly and after differentiation is used to indicate the end-point. Total carbon dioxide (C milliequivelents per litre of HCO3 per litre) is determined by mixing the sample with dilute sulfuric acid and segmenting it with carbon dioxide-free air, so that the carbon dioxide in the sample is expelled into the air segments. The air... 

Maye et al. studied gold nanoparticles supported on carbon black for ORR in both acidic and alkaline media.210 The gold nanoparticles were of a core-shell type where the particle consisted of a gold nanocrystal core of 1-6 nm in diameter that was surrounded by an organic monolayer shell.214 While the Au/C catalyst was found to be active for ORR, its activity was much lower than that of Pt/C, PtRu/C and AuPt/C. The electron transfer in 0.5 M H2S04 was reported as 2.9 0.2, indicating a mixed reduction pathway.210... 

RP-HPLC found application in the monitoring of the alkali hydrolysis kinetics of alkali-clearable azo disperse dyes containing a fluorosulphonyl group. The chemical structures of dyes included in the experiments are shown in Fig. 3.85. Samples for RP-HPLC analysis were neutralized to pH 4.0 - 4.5 with diluted HC1 mixed with five volumes of ACN and injected without any other sample preparation step. Separation was carried out in an ODS column at ambient temperature. The isocratic mobile phase consisted of ACN-water (80 20, v/v) and dyes were detected at their absorption maxima. HPLC measurements indicated that dyes are easily hydrolysed under relatively mild alkaline conditions, and the hydrolysis follows a pseudo first-order kinetics [148],... 

The nanostructured Au and AuPt catalysts were found to exhibit electrocatalytic activity for ORR reaction. The cyclic voltammetric (CV) curves at Au/C catalyst reveal an oxidation-reduction wave of gold oxide at +200 mV in the alkaline (0.5 M KOH) electrolyte but little redox current in the acidic (0.5 M H2SO4) electrolyte. Under saturated with O2, the appearance of the cathodic wave is observed at -190 mV in the alkaline electrolyte and at +50 mV in the acidic electrolyte. This finding indicates that the Au catalyst is active toward O2 reduction in both electrolytes. From the Levich plots of the limiting current vs. rotating speed data, one can derive the electron transfer number (w). We obtained n = 3.1 for ORR in 0.5 M KOH electrolyte, and 2.9 for ORR in 0.5 M H2SO4 electrolyte. The intermittent n-value between 2 and 4 indicates that the electrocatalytic ORR at the Au/Ccatalyst likely involved mixed 2e and 4e reduction processes. 

In this method, sodium sulfide, potassium sulfide, and/or ferrous sulfide can be dosed to the spent fixer during mixing at an alkaline pH range, for precipitation of silver ions as insoluble silver sulfide precipitates [87]. Figure 7 [19,59] indicates that the residual silver concentration in the sulfide precipitation treated effluent can be below 10 mg/L in the entire alkaline range, and can be as low as 10 mg/L at pH 10.5. 

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