Hydrochloric acid titration with ammonia

A 0.400 M solution of ammonia was titrated with hydrochloric acid to the equivalence point, where the total volume was 1.50 times the original volume. At what pH does the equivalence point occur ... 

The concentration of aqueous ammonia in a cleaning solution is determined hy titration with hydrochloric acid. A volume of 23.18 mL of 0.8381 M HCl is needed to titrate a... 

Comparing the two titration curves one can recognize that the steepness of the titration curve at the equivalence point is much larger in case of the titration of ammonia with hydrochloric acid, than for the case of titration of ammonium ions with sodium hydroxide. This means that the random errors will be much smaller when ammonia is titrated with hydrochloric acid, and this titration is strongly to be preferred. 

The precipitated acetyHde must be decomposed with hydrochloric acid after the titration as a safety measure. Concentrated solutions of silver nitrate or silver perchlorate form soluble complexes of silver acetyHde (89). Ammonia and hydrogen sulfide interfere with the silver nitrate method which is less... 

In many titrations, one solution—either the analyte or the titrant—contains a weak acid or base and the other solution contains a strong base or acid. For example, if we want to know the concentration of formic acid, the weak acid found in ant venom (1), we can titrate it with sodium hydroxide, a strong base. Alternatively, to find the concentration of ammonia, a weak base, in a soil sample, titrate it with hydrochloric acid, a strong acid. Weak acids are not normally titrated with weak bases, because the stoichiometric point is too difficult to locate. 

Because the salt has a basic anion, we can expect the pH to be greater than 7 at the stoichiometric point. At the stoichiometric point of the titration of aqueous ammonia with hydrochloric acid, the solute is ammonium chloride. Because NH4+ is an acid, we expect the solution to be acidic with a pH of less than 7. The same is true for the stoichiometric point of the titration of any weak base and strong acid. 

Name an indicator you might use to titrate ammonia with hydrochloric acid. 

The titration of a weak base with a strong acid is completely analogous to the above case, but the titration curves are the reverse of those for a weak acid versus a strong base. The titration curve for 100 mL of 0.1 M ammonia titrated with 0.1 M hydrochloric acid is shown in Figure 8.8. The neutralization reaction is... 

What would be a suitable indicator for the titration of ammonia with hydrochloric acid Of acetic acid with sodium hydroxide ... 

This example is aimed at illustrating that titration curves may be significantly different for the case that an acid is titrated and the case where the corresponding base is titrated. Fig. 83 displays the titration curves for ammonium ions with sodium hydroxide and ammonia with hydrochloric acid. 

Fig. 83 Titration diagram of ammonia with hydrochloric acid orange line) and ammonium ions (e.g., ammonium chloride) with sodium hydroxide black line) (logC° = —1, = 9.25)...

Figure 85 illustrates how the relevant data can be read from a pH-logCj diagram using the example of a titration of ammonia with hydrochloric acid. 

Table 5 Systematic errors in case of the titration of ammonia (C2 ,o ia = 0.1 mol L ) with hydrochloric acid when using different indicators. The concentration data are taken from Fig. 85 ...

The range of applications of potentiometric titrations for determination of acids and bases is very wide, as illustrated by the following examples. Carbonate, hydrogencarbonate, and hydroxide ions are all bases that can be titrated with a strong acid such as hydrochloric acid. The most popular method for determination of nitrogen, which is found in many important substances such as proteins, fertilizers, drugs, pesticides, natural waters, is the Kjeldahl method, based on the conversion of the bound nitrogen to ammonia, which is then separated by distillation and determined by titration with hydrochloric... 

Psychotrine is not soluble in ether, hence, after extraction of the emetine in sodium hydroxide solution, which retains phenolic bodies, acidify the aqueous residues with hydrochloric acid and then make alkaline with ammonia. Extract the cephaeline completely with ether and titrate as with emetine. 1 ml 0-1N = 0-0233 g. Finally, extract the ammoniacal residues with chloroform for psychotrine. 1 ml 0-02N - 0 00464 g. 

Reduction. Triaryknethane dyes are reduced readily to leuco bases with a variety of reagents, including sodium hydrosulfite, 2inc and acid (hydrochloric, acetic), 2inc dust and ammonia, and titanous chloride in concentrated hydrochloric acid. Reduction with titanium trichloride (Knecht method) is used for rapidly assaying triaryknethane dyes. The TiCl titration is carried out to a colorless end point which is usually very sharp (see Titanium COMPOUNDS, inorganic). 

A1C13, or S02 in an inert solvent cause colour changes in indicators similar to those produced by hydrochloric acid, and these changes are reversed by bases so that titrations can be carried out. Compounds of the type of BF3 are usually described as Lewis acids or electron acceptors. The Lewis bases (e.g. ammonia, pyridine) are virtually identical with the Bransted-Lowry bases. The great disadvantage of the Lewis definition of acids is that, unlike proton-transfer reactions, it is incapable of general quantitative treatment. 

The monoethanolamine-hydrochloric acid buffer has a buffering capacity equal to the ammonia-ammonium chloride buffer commonly employed for the titration of calcium and magnesium with EDTA and solochrome black (compare Section 10.54). The buffer has excellent keeping qualities, sharp end points are obtainable, and the strong ammonia solution is completely eliminated. 

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). 

It may be noted that very weak acids, such as boric acid and phenol, which cannot be titrated potentiometrically in aqueous solution, can be titrated conductimetrically with relative ease. Mixtures of certain acids can be titrated more accurately by conductimetric than by potentiometric (pH) methods. Thus mixtures of hydrochloric acid (or any other strong acid) and acetic (ethanoic) acid (or any other weak acid of comparable strength) can be titrated with a weak base (e.g. aqueous ammonia) or with a strong base (e.g. sodium hydroxide) reasonably satisfactory end points are obtained. 

The pH of a 50.00-mL sample of 0.1100 M ammonia, NH3, is measured as it is titrated with a 0.1100 M hydrochloric acid, HC1. Determine the pH of the solution after the following total volumes of hydrochloric acid have been added. 

Procedure Weigh accurately about 0.8 g of granulated zinc, dissolve by gentle warming in 12 ml of dilute hydrochloric acid and 5 drops of bromine water. Boil to remove excess bromine, cool and add sufficient DW to produce 200 ml in a volumetric flask. Pipette 20 ml of the resulting solution into a flask and neutralize carefully with 2 N sodium hydroxide. Dilute to about 150 ml with DW, add to it sufficient ammonia buffer (pH 10.0) to dissolve the precipitate and add a further 5 ml quantity in excess. Finally add 50 mg of Mordant Black II mixture and titrate with the disodium edetate solution until the solution turns green. Each 0.003269 g of granulated zinc is equivalent to 1 ml of 0.05 M disodium ethylenediaminetetracetate. 

Elemental composition Na 58.93%, N 35.90%, H 5.17%. The compound may he decomposed cautiously with water (reaction is violent) under cooling to yield sodium hydroxide and ammonia. (Or it may he decomposed with anhyrous alcohol to form ammonia and sodium alcoholate. The alcoholate then may he treated with water to form sodium hydroxide). Ammonia liberated is dissolved in water and the solution is measured using an ammonia-selective electrode. Alternatively, ammonia is collected over horic acid solution containing a small quantity of methyl red indicator. The solution is titrated with a standard solution of sulfuric acid. Sodium hydroxide is measured hy titration with a standard solution of hydrochloric or sulfuric acid. 

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