Equivalent of an acid

By Titration with Standard Alkali.—— aqueous and alcoholic potash 

The baryta solution is prepared from pure crystalline barium hydroxide, Ba(0H)2.8H20, by dissolving in distilled water. Any carbonate is allowed to subside and the clear supernatant liquor syphoned into the storage bottle after the latter has been filled with air free from carbon dioxide. 

To determine the equivalent of an acid, a suitable quantity of it—determined by trial titrations—is dissolved in distilled water if soluble in water, and if insoluble in water in aqueous alcohol, or in alcohol free from acid. The average of a few readings which should agree to within 0-5% is taken, and the amount of acid necessary to neutralise 85-5 gms. of barium hydroxide calculated. 

When the sodium or potassium salt is available in a pure state, a known weight is ignited until only a residue of pure carbonate remains. A few drops of cone, sulphuric acid are then carefully added, and heat from a small flame applied until the excess of sulphuric acid is driven off. If any specks of carbon remain the last process is repeated. Finally the residue is weighed as alkali sulphate. 

When an acid contains halogen, and the silver salt method is employed, the residue after ignition is treated with a few drops of nitric acid and a little ammonium halide to ensure complete conversion into silver halide. 

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CjHiaNO, [Mc3NCH= CH2] OH. A liquid forming a crystalline trihydrate, It is present free and combined in brain and other animal and vegetable products and is formed as a product of putrefaction of lecithin. It can be prepared synthetically from choline and decomposes easily to trimethylamine. neutralization, heat of The amount of heat evolved when I g equivalent of an acid is neutralized by 1 g equivalent of a base. For strong acids and strong bases in dilute solution the only reaction which occurs is H -h OH ---> H2O and the heat of neutral-... 

Neutralisation reactions. The equivalent of an acid is that mass of it which contains 1.008 (more accurately 1.0078) g of replaceable hydrogen. The equivalent of a monoprotic acid, such as hydrochloric, hydrobromic, hydriodic, nitric, perchloric, or acetic acid, is identical with the mole. A normal solution of a monoprotic acid will therefore contain 1 mole per L of solution. The equivalent of a diprotic acid (e.g. sulphuric or oxalic acid), or of a triprotic acid (e.g. phosphoric( V) acid) is likewise one-half or one-third respectively, of the mole. 

A misconception that we commonly encounter is that a spectrum can be a mixture of the salt and the free base. This is an excuse that is often used by chemists to explain an inconveniently messy looking spectrum Don t be tempted by this idea - proton transfer is fast on the NMR timescale (or at least, it is when you use a polar solvent ) and because of this, if you have a sample of a compound that contains only half a mole-equivalent of an acid, you will observe chemical shifts which reflect partial protonation and not two sets of signals for protonated and free-base forms. It doesn t happen - ever ... 

For the synthesis of benzoxazoles, Player and coworkers have developed a simple method that involves microwave heating of a 2-aminophenol with 1.1 equivalents of an acid chloride in dioxane or xylene (Scheme 6.213) [384]. The best results were... 

The method is a general one and can be applied to esters to determine the equivalent of an acid combined in them. Ester equivalent = a. 1000/6 where a is the weight of ester taken (in grammes) and 6 is the number of c.c. of A-alkali used up. 

Monoderivatives of symmetrical diols.2 One possible route to these derivatives is treatment of the diol with di-n-butyllin oxide to form a stannoxane, which is then allowed to react with 1 equivalent of an acid chloride or sulfonyl chloride (equation I). L nsymmetrical diesters can be obtained by consecutive reaction of the stannoxane wilh two different reagents. 

The alcohol is added3 to a ca. 0.4—1 M solutionb of ca. 1-10 equivalents— typically 1.1 3 eq.—of IBXC in DMSO.d,e In the oxidation of substrates containing a primary or secondary amine, ca. 1 1.5 equivalents of an acid such as TFA must be added for protection. When a TLC analysis shows that most of the starting compound is consumed/ the reaction is elaborated according to two alternative protocols ... 

Ammonium ion and Valency.—Although no direct measurement of the electroaffinity of the ammonium ion has been possible, the slight tendency to hydration of its salts indicates that it is stronger than the potassium ion. It is colourless, and the migration-velocity at 18° C.3 is given as 64-2, and at 25° C.4 as 73. Like the alkali-metals, the radical ammonium is univalent, and forms salts with one equivalent of an acid. 

Normality (N) is the number of equivalents of the solute per liter of solution. A1.0 N solution of acid (or base) contains one equivalent of an acid (or base) per liter of solution. A 1.0 M solution of HCl is 1.0 N, but a 1.0 M solution of H2SO4 is 2.0 N. Sulfriric acid has two acidic hydrogens, and the molarity is multiplied by a factor of 2. Phosphoric acid (H3PO4) is triprotic (having three protons it can donate) and a 1.0 molar solution is 3.0 normal. 

If an ester is hydrolyzed in a known amount of base (taken in excess), the amount of base used up can be measured and used to give the saponification equivalent the equivalent weight of the ester, which is similar to the neutralization equivalent of an acid (sec Sec. 18.21). 

In the presence of D2O microsomes of maize embryos convert cycloeucalenol (44) into [19- H]obtusifoliol (45). This reaction is the biochemical equivalent of an acid-catalysed opening of the cyclopropane ring. The resonances of some actein and cimigoside derivatives have been assigned. ... 

Dimethyloxosulfonium methylide can be acylated by treatment of 2 equivalents of reagent with 1 equivalent of an acid chloride to give a stable /3-ketooxosulfonium ylide such as (1, m.p. 120°). These are of interest because upon excitation with 253... 

Note A water solution containing one equivalent of an acid, base, or salt in one liter of solution is a one normal (IN) solution. 

From the definitions of one equivalent of an acid and of a base, we see that one equivalent of an acid reacts with one equivalent of any base. It is not true that one mole of any acid reacts with one mole of any base in any specific chemical reaction that goes to completion. As a consequence of the definition of equivalents, 1 eq acid s 1 eq base. We may write the following for all acid-base reactions that go to completion. 

For acid-base reactions, an equivalent of an acid is the quantity that supplies 1 mol of H and an equivalent of a base is the quantity reacting with 1 mol of H ... 

The equivalent weight of a base may be defined as the number of parts by weight of the base that neutralise one equivalent of an acid. 

That is to say, at the anode there is an equivalent of an acid, and at the cathode an equal amount of a base, formed for every faraday passed through the solution. Evidently if the solutions around the two electrodes are allowed to mix, the current efficiency of the production of these substances will be lowered. 

Normality is another unit of concentration that is sometimes used, especially when dealing with acids and bases. The use of normality focuses mainly on the H and OH" available in an acid-base reaction. Before we discuss normality, however, we need to define some terms. One equivalent of an acid is the amount of that acid that can furnish 1 mol ofH ions. Similarly, one equivalent of a base is defined as the amount of that base that can furnish 1 mol ofOH ions. The equivalent weight of an acid or a base is the mass in grams of 1 equivalent (equiv) of that acid or base. 

Neutralization reaction Equivalent of an acid Equivalent of a base Equivalent weight Colligative property... 

Equivalent of an acid the amount of acid that can furnish one mole of hydrogen ions (H ). 

Equivalent weight the mass (in grams) of one equivalent of an acid or a base. 

The investigations with diazenolates were made in water and ethanol. Diazeno-lates can also be decomposed, however, in aprotic solvents by addition of one equivalent of an acid HX. An ion pair is formed that contains one water molecule. Deaminations by this route have been investigated mainly by Moss (review Moss, 1974). 

The equivalent of an acid is that quantity which will form a neutral salt with one equivalent of a base and, in like manner, the equivalent of a base is that (quantity which forms a neutral salt with one equivalent of an acid. 

The heat of neutralisation is the amount of heat evolved when one gram equivalent of an acid is neutralised by one gram equivalent of a base to give one gram equivalent of a neutral salt. Thus, in dilute solution, an acid or base is considered to be completely ionised, and the neutralisation reaction is Na + ) + OH(-) + H( + ) + Q(-) ==> Na(+) + a(-) + P... 

An equivalent is defined according to the type of reaction being examined, but the number of equivalents of solute is always a whole number multiple of the number of moles of solute, and so the normality of a solute is always a whole-number multiple of its molarity. An equivalent is defined so that one equivalent of one reagent will react with one equivalent of another reagent. For acid-base reactions (see competency 7), an equivalent of an acid is the quantity that supplies 1 mol of and an equivalent of a base is the quantity reacting with 1 mol of... 

What is one equivalent of an acid What does an equivalent of a base represent How is the equivalent weight of an acid or a base related to the substance s molar mass Give an example of an acid and a base that have equivalent weights equal to their molar masses. Give an example of an acid and a base that have equivalent weights that are not equal to their molar masses. What is a normal solution of an acid or a base How is the normality of an acid or a base solution related to its molarity Give an example of a solution whose normality is equal to its molarity, and an example of a solution whose normality is not the same as its molarity. 

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