Stoichiometrically equivalent quantities

The combined liquors, which comprise an aqueous hydrochloric acid solution of 3-amino-methyl-pyridine hydrochloride, are then heated to a temperature of 60° to 65°C, and ethyl nitrite gas is passed into the heated solution. The ethyl nitrite is generated by placing 20 liters of 90% ethyl alcohol in a suitable vessel, diluting with 200 liters of water, and, while stirring, adding to the dilute alcohol 18.3 kg of nitrosyl chloride at the rate of 2.25 kg per hour. (The process using methyl nitrite is carried out by substituting a stoichiometrically equivalent quantity of methyl alcohol for the ethyl alcohol.)... 

The quantities 2 mol H2, 1 mol O2, and 2 mol H2O given by the coefficients in Equation 3.12 are called stoichiometrically equivalent quantities. The relationship between these quantities can be represented as... 

To determine the concentration of a particular solute in a solution, chemists often carry out a titration, which involves combining a solution where the solute concentration is not known with a reagent solution of known concentration, called a standard solution. Just enough standard solution is added to completely react with the solute in the solution of unknown concentration. The point at which stoichiometrically equivalent quantities are brought together is known as the equivalence point. 

SECTION 4.6 In the process called titration, we combine a solution of known concentration (a standard solution) with a solution of unknown concentration to determine the unknown concentration or the quantity of solute in the unknown. The point in the titration at which stoichiometrically equivalent quantities of reactants are brought together is called the equivalencs point. An indicator can be used to show the end point of the titration, which coincides closely with the equivalence point. 

When a mixture of reactants undergoes treatment in a reactor and more than one product is formed, part of each reactant is converted into the desired product, part is converted into undesired products and the remainder escapes unreacted. The amount of the desired product actually obtained is therefore smaller than the amount expected had all the reactant been transformed into the desired product alone. The reaction is then said to give a certain yield of the desired product. Unfortunately, the term yield has been used by different authors for two somewhat different quantities and care must be taken to avoid confusion. Here these two usages will be distinguished by employing the terms relative yield and operational yield in each case the amount of product formed will be expressed in terms of the stoichiometrically equivalent amount of the reactant A from which it was produced. 

In the laboratory it is prepared by the action of methanol on chlorosulphonic acid. According to Claesson, the chlorosulphonic acid is placed in a small flask, which is fitted with a tap-funnel and externally cooled with ice. Water-free methyl alcohol, previously distilled from lime, is slowly introduced in quantity stoichiometrically equivalent to the chlorosulphonic acid. As each drop of alcohol comes into contact with the chlorosulphonic acid, hydrochloric acid is evolved. At the end of addition of the alcohol the flask is heated gently while a current of dry air is passed through in order to remove the hydrochloric acid dissolved in the mixture. The product obtained contains about 90% methyl sulphuric acid. 

The oxidation of a substrate by any Pd species in principle is a stoichiometric reaction, consuming first of all molar amounts of the Pd present, thus forming equivalent quantities of Pd°. If catalytic oxidative carbonylations are required with respect to the palladium compound, appropriate conditions for the reoxidation of Pd have to be found. This may be achieved by the presence of suitable co-catalysts, for example of certain transition metal salts, which are capable of changing their oxidation state. 

Calculations of volumetric analysis ordinarily consist of transforming the quantity of titrant used (in chemical units) to a chemically equivalent quantity of analyte (also in chemical units) through use of a stoichiometric factor. Use chemical formulas (NO CALCULATIONS REQUIRED) to express this ratio for calculation of the percentage of (a) hydrazine in rocket fuel by titration with standard iodine. Reaction ... 

It is evident from the above that each of the amines of a group has a different dissociation constant and therefore a different basicity. I have found that this fact enables me to accomplish a separation of certain of the amines from the others. Even though each of the primary, secondary and tertiary amines in one group has a different basicity, it is not economically feasible with any process to separate those which have approximately the same basicity, for example, in the case of the methyl-amines, it is entirely practical to treat a mixture of the three amine salts with a quantity of alkali stoichiometrically equivalent to the trimethy-lamine present in the mixture and subsequently to boil out or otherwise remove the liberated trimethylamine. It is not, however, economically possible to obtain a sharp separation by treating the resulting residue of mono and dimethylamine saits with a further quantity of alkali equivalent to the monomethylamine and boil - the solution to obtain monomethylamine. The difference in basicity between the mono and dimethylamines is so small that good separation is not obtained. 

In Chapters 3 and 4, we encountered many reactions that involved gases as reactants (e.g., combustion with O2) or as products (e.g., a metal displacing H2 from acid). From the balanced equation, we used stoichiometrically equivalent molar ratios to calculate the amounts (moles) of reactants and products and converted these quantities into masses, numbers of molecules, or solution volumes (see Figure 3.10). Figure 5.11 shows how you can expand your problem-solving repertoire by using the ideal gas law to convert between gas variables (F, T, and V) and amounts (moles) of gaseous reactants and products. In effect, you combine a gas law problem with a stoichiometry problem it is more realistic to measure the volume, pressure, and temperature of a gas than its mass. 

Just as we use stoichiometrically equivalent molar ratios to find amounts of substances, we use thermochemically equivalent quantities to find the heat of reaction for a given amount of substance. Also, just as we use molar mass (in g/mol of substance) to convert moles of a substance to grams, we use the heat of reaction (in kJ/mol of substance) to convert moles of a substance to an equivalent quantity of heat (in kJ). Figure 6.9 shows this new relationship, and the next sample problem applies it. 

If we assume that the reaction mentioned in Section 10.3.2 is a fundamental description of the processes controlling the concentration of DOC in groundwater, then this reaction would also control the concentration of iron in groundwater at the same time. An easy way to check this was to run two model calculations, both with identical model parameters. However, one of these calculations was run without considering the reduction of DOC. In this case the distribution of DOC is only controlled by the input from the river Oder and the physical transport with advection and dispersion along the flow through the aquifer. The difference between calculated distribution of concentration with reaction and distribution calculated at same conditions but without reduction of DOC will show the reduced quantity of DOC for each point of the flow field. Now this quantity can be converted stoichiometricly into the equivalent quantity of dissolved iron. Thus one mol of CO2 from oxidised DOC corresponds with four times the amount of used iron(III)oxide and the resulting Fe + in solution. 

A 7-g quantity of manganese and chromium metals as their nitrate salts, which metals are in the stoichiometric equivalent proportions required to form manganese chromite, is added to 950 ml of water at 90°C. The mixture is stirred... 

Aliphatic polyamides are produced commercially by condensation of diamines with dibasic adds, by self-condensation of an amino acid, or by self-condensation of an amino acid, or by ring-opening polymeri2ation of a lactam [14,40,41]. To obtain polymers of high molecular weight, there should be stoichiometric equivalence of amine and acid groups of the monomers. For amino acids and lactams the stoichiometric balance is ensured by the use of pure monomers for diamines and dibasic acids this is readily obtained by the preliminary formation of a 1 1 ammonium salt, often referred to as a nylon salt. Small quantities of monofunctional compounds are often used to control the molecular weight. 

We will begin by discussing a number of important formulae for converting common process variables involving moles to equivalent quantities involving mass fraction. These concepts are not difficult to understand, however, they are fundamental to how the computation of ARs in mass fraction space must be organized. Discussion of how the stoichiometric subspace may be computed and how residence time may be incorporated in mass fraction space is also provided. From this, a number of examples are provided that demonstrate the theory. In particular, isothermal and nonisothermal unbounded gas phase systems shall be investigated. 

It should be emphasized again that the theoretical amounts refer to the stoichiometric equivalents after a complete combustion. This is never the case in practice, when lesser or greater fractions of these quantities appear, depending on the burning conditions. 

Thus pFe2+ changes from 4.3 to 10 between 0.1 per cent before and 0.1 per cent after the stoichiometric end point. These quantities are of importance in connection with the use of indicators for the detection of the equivalence point. 

Stoichiometrically, the total quantity of electricity passed is exactly the same as it would have been if the Fe(II) ions had been directly oxidised at the anode and the oxidation of Fe(II) proceeds with 100 percent efficiency. The equivalence point is marked by the first persistence of excess Ce(IV) in the solution, and may be detected by any of the methods described above. The Ce3+ ions added to the Fe(II) solution undergo no net change and are said to act as a mediator. 

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