Phenolphthalein test

The final residue from the mother liquor is an oil which does not solidify in a freezing mixture, and appears to be a mixture of p- and w-tolylcarbinols. Only a trace of phthalic acid (phenolphthalein test) was obtained by oxidizing this oil with permanganate the portion of it which was more readily soluble in water yielded a phenylurethan which depressed the melting point of the phenylurethan of either />-tolylcarbinol or benzyl alcohol. 

Sodium carbonate-phenolphthalein test This test depends upon the fact that phenolphthalein is turned pink by soluble carbonate and colourless by soluble bicarbonates. Hence if the carbon dioxide liberated by dilute acids from carbonates is allowed to come into contact with phenolphthalein solution coloured pink by sodium carbonate solution, it may be identified by the decolourization which takes place... 

The results of the phenolphthalein test show that the pH falls to 8.5 or below in the carbonated zone, but no more detailed studies on the composition of the pore solution have been reported. Andrade ct al. (A33) concluded that a value as low as 8.5 could only be explained if alkali cations were removed from the solution by leaching or uptake by the hydrous silica... 

Remove the soap from the beaker. Add to a piece of it a drop of a solution of phenolphthalein. Test in the same way a piece of pure toilet soap. (1) Give a reason for the dilference observed. (2) Write an equation for a reaction involved in the preparation of soap from lard, which contains the glycerine ester of stearic acid. 

Why all the concern Because caustic sodium hydroxide (lye) can form as a by-product of the chemical reaction that inflates an air bag, and officials at the scene thought that the white powder released was sodium hydroxide. It was actually talctun powder, which air bag manufacturers use as a lubricant. The investigators could have determined that sodium hydroxide was not present at the scene of the accident if they d performed the simple phenolphthalein test. 

Kastle Meyer test (phenolphthalein test) A presumptive test used to indicate blood. Phenolphthalein and hydrogen peroxide are used reaction with haemoglobin in the blood gives a pink colour. 

Areas where carbonation has ingressed to within 5 mm of the reinforcement. The depth of carbonation can be determined by testing the concrete with phenolphthalein, which turns pink in an alkaline environment and remains colorless in a carbonated environment. The depth of carbonation can also be determined by Depth of carbonates = (age in years) at 50% RH and (age in years) in about 90% RH. The test surface must be a fracture surface, not drilled (as grinding invalidates the phenolphthalein test). 

Phthalein reaction. Fuse together carefully in a dry test-tube a few crystals of phthalic acid or of a phthalate and an equal quantity of ph tol moistened with 2 drops of cone. H2SO4. Cool, dissolve in water and add NaOH solution in excess the bright red colour of phenolphthalein in alkaline solution is produced. 

Sorensen s reaction. First read carefully the Estimation of Glycine, p. 463. Dissolve 0 2 g. of glycine in a few ml. of water in a test-tube A, add 2 drops of phenolphthalein and then very dilute NaOH solution drop by drop until the solution just turns pink. In a second test-tube B place 2 ml. of 40% formalin solution, add 2 drops of phenolphthalein solution and then the dil. NaOH solution until the solution just turns pink. Pour the contents of B into A and note the immediate decolorisation of the phenolphthalein, the solution now being acid. Observe also that several drops of dil. NaOH solution can now be added before the pink colour is restored. 

Tyrosine and cystine are insoluble in water therefore place about 0 2 g. in the test-tube A, dissolve in the dil. NaOH solution, add phenolphthalein as before and then add dil. HCl until pink colour is iust not discharged then proceed as above. 

Acidify the residue in the flask with dUute sulphuric acid and distil off 10-15 ml. of the solution. Test a smaU portion of the distillate for acidity, and also observe the odour. Neutralise the main portion with sodium hydroxide solution (add a drop of phenolphthalein to act as indicator), evaporate to smaU bulk, and convert the sodium salt into the p-bromophenacyl ester or into some other suitable derivative (Section 111,85) determine the m.p. of the derivative. 

The sodium sulphite solution may also be prepared by dissolving 100 g. of pure (or a corresponding quantity of commercial) sodium hydroxide in about 125 ml. of water, and then diluting to 750 ml. The flask is cooled in running water, a few drops of phenolphthalein indicator are added, and sulphur dioxide passed in until the pink colour just disappears (it is advisable to add a further 1-2 drops of the indicator at this point) and then for 2-3 minutes longer. It is best to remove a sample for test from time to time, dilute with 3-4 volumes of water, and test with I drop of phenolphthalein. 

Detecting the presence of small, even invisible, amounts of blood is routine. Physical characteristics of dried stains give minimal information, however, as dried blood can take on many hues. Many of the chemical tests for the presence of blood rely on the catalytic peroxidase activity of heme (56,57). Minute quantities of blood catalyze oxidation reactions between colorless materials, eg, phenolphthalein, luco malachite green, luminol, etc, to colored or luminescent ones. The oxidant is typically hydrogen peroxide or sodium perborate (see Automated instrumentation,hematology). 

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 HCl to the phenolphthalein end point 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 CaCO,. 

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. 

Another recipe for a universal indicator is as follows 0.05 g of methyl orange, 0.15 g of methyl red, 0.3 g of bromothymol blue, and 0.35 g of phenolphthalein in 1 L of 66 per cent ethanol. The colour changes are pH up to 3, red pH 4, orange-red pH 5, orange pH 6, yellow pH 7, yellowish-green pH 8, greenish-blue pH 9, blue pH 10, violet pH 11, reddish-violet. Several universal indicators are available commercially as solutions and as test papers. 

Benzoic acid is sparingly soluble in water (which is a disadvantage) and must therefore be dissolved in 95 per cent ethanol. The mode of use is similar to that already described for potassium hydrogenphthalate (Section 10.27, Procedure B). For a 0.1 M solution, of, say, sodium hydroxide, weigh out accurately 0.4 g portions of the acid into a 250 mL conical flask, add 10- 20 mL of ethanol, shake until dissolved, and then titrate the solution with the strong alkali using phenolphthalein as indicator. A blank test should be made with the same volume of ethanol and the indicator deduct, if necessary, the volume of the alkali solution consumed in the blank test. 

NOTE Acid phosphates and SHMP may attack chemical tanks and associated equipment, so acid-resistant equipment should be specified. Alternatively, the addition of caustic up to a pH level of 8.2 to 8.3 (the production of a pink color when tested with phenolphthalein) provides adequate protection. A further alternative is to add neutralizing amine to the tank. 

Alkalinity is measured by acid-base titration with methylorange or phe-nolphthalein as indicator. Phenolphthalein changes color at pH 8.3, whereas methylorange changes color at pH 4.3. At pH 8 the neutralization of the strong alkali ingredients like NaOH is essentially complete. Further reduction of the pH to 4 will also measure carbonates and bicarbonates. Colorimetric tests and glass electrode systems are used to determine pH. 

Add 2 drops of phenolphthalein solution to each solution in each of the numbered test tubes. 

Place 2 drops of phenolphthalein in both the test tube and the beaker. 

Even the police make use of acids and bases to catch criminals. For example, forensic scientists can compare soil pH found at a crime scene with trace amounts of soil found on a tire tread or shoe bottom. They also use a mixture of hydrogen peroxide and phenolphthalein called Kastle-Meyer solution to test for blood. Kastle-Meyer solution is used at a crime scene when crime scene specialists find spots they suspect could be dried blood. The solution turns bright pink in the presence of blood. If the spots turn out to be something else, such as dried tomato sauce or reddish-brown paint, the Kastle-Meyer solution remains colorless. 

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