Amount of a species

An equation stating that matter is conserved, and that the total amount of a species added to a solution must equal the sum of the amount of each of its possible forms present in solution. 

Choosing the basis in this manner sometimes leads to some initial confusion, because we select species present in the system to serve as components. There is a risk of confusing the amount of a component, which describes bulk composition but not the actual state of the system, with the amount of a species or mineral that exists in reality. 

The chemical potential // can be thought of as the constant of proportionality between a change in the amount of a species and the resultant change in the Gibbs function of a system. 

Often, to simplify the measurement of n, the current recorded on the process under examination is compared with that given, under the same experimental conditions, by an equimolar amount of a species whose n is known. This is really a good and simple method, but it requires that the compared species possess a comparable diffusion coefficient D (i.e. in first instance, the species used for comparison must possess a molecular weight roughly similar to that of the species under examination). 

The detection limit for measuring a species by filter collection and subsequent analysis is determined either by the uncertainty in the filter blank, that is, the variability in the amount of a species in an unexposed filter, or by the limit of detection imposed by the analytical method. Most frequently, the limit of detection is determined by blank variability, thus care in preparation and handling of filters is important when using such systems for aircraft sampling, particularly if sampling is conducted in remote areas where concentrations are low. In this regard, it is crucial to establish the blank... 

The Stern-Volmer equation (see sect. 4) may be used to determine small amounts of a species which would behave as an inhibitor of a given luminescent probe. The detection limit depends, among other parameters, on and on the detection limits of the setup. The potentials of this method for analytical purposes are discussed, on a general aspect, in Borissevitch (1999), Rakicioglu et al. (1998) and the specific cases of Eu(III) or U(VI) are presented in Georges (1993), Lopez and Birch (1996), Kessler (1998). For example, a detection limit of 7 ngl-1 for Cu2+ is obtained (Lopez and Birch, 1996). Numerous factors may render the method difficult to apply besides the variations of ksv as a function of ionic strength, if more than one quencher is present in solution, it becomes difficult to determine their individual concentrations. This problem has been studied in the case of solutions that more or less mimic the nuclear fuel solutions in Katsumura et al. (1989). 

Thus, for 2 one-electron steps the second transition time is three times as long as the first. For a one-electron step followed by a two-electron step the ratio increases to 8. In contrast to polarography, chronopotentiometiy offers enhanced analytical sensitivity for a second (or third) species. Advantage of this characteristic can be taken by adding a known amount of a species electrolyzed prior to the unknown species in some cases this can provide a tenfold increase in sensitivity. 

For a liquid-solid catalytic reaction the common technique for determining the adsorbed amount of a species dissolved in the solution is that of performing experiments in a batch not-reacting system and of measuring ... 

Dissolution refers to the partitioning of chemical species between gas-liquid and liquid-liquid phases. Assuming local equilibrium partitioning, the maximum amount of a species that will dissolve into a liquid at a given temperature is given by its solubility. When local equilibrium is not achieved, a rate-limited mass transfer expression is used. For example. Miller, Poirzer-McNeill, and Mayer present a common rate-limited... 

It is generally observed that as the concentration of a species in solution increases, the amount of it sorbed (attached in some way) to contacting solid (sorbent) surfaces also increases. A plot that describes the amount of a species sorbed (the sorbate) as a function of its concentration in solution, measured at constant temperature, is called a sorption isotherm. A simple sorption isotherm is shown... 

For convenience, the amount of a species in solution is often expressed as a molality rather than as a mole fraction. The molality of a solute is its amount in moles per kilogram of solvent. For an aqueous solution containing n moles of solute and nw moles of water (molecular weight 0.018 kg mol-1) the molality, m, , of the solute is... 

The important chemical difference between flames and other flow reaction systems is that the radical species required to initiate reactions need not be generated locally. They can be transported from high-temperature stages back to the early or low-temperature regions by diffusion. These qualitative differences can be best appreciated by considering the two composition variables used to describe flow systems concentration (/), the amount of a species per unit volume, and flux (G), the amount of a species... 

The combination of both operators, elastance and conductance, is not indicated on the Formal Graph as it was done for a pole (see case study All in Chapter 4) because it does not correspond to the usual practice for a set of several reactions as is the case here. On the contrary, at the level of a single pole, it is customary in chemistry to relate directly the substance amount of a species / to the substance flow (or reaction rate) through a proportionality factor called rate constant or specific rate of reaction k,. 

Gravimetric analysis is a type of quantitative analysis in which the amount of a species in a material is determined by converting the species to a product that can be isolated completely and weighed. Precipitation reactions are frequently used in gravimetric analyses. In these reactions, you determine the amount of an ionic species by precipitating it from solution. The precipitate, or solid formed in the reaction, is... 

Quantitative analysis involves the determination of the amount of a species in a material. In gravimetric analysis, you determine the amount of a species by converting it to a product you can weigh. In volumetric analysis, you determine the amount of a species by titration. Titration is a method of chemical analysis in which you measure the volume of solution of known molarity that reacts with a compound of unknown amount. You determine the amount of the compound from this volume of solution. 

Determining the amount of a species by gravimetric analysis Given the amount of a precipitate in a gravimetric analysis, calculate the amount of a related species. (EXAMPLE 4.12)... 

Thus, the amount of a species j is defined as the Faraday s weight gained or hberated due to the flowing electric current during a period of time... 

The permeability aims at measuring over a time-period the amount of a species crossing a polymer film subjected to a difference in potency of the species (Soares et al., 1999 Listen and Hedenqvist, 2003). Permeability properties of a polymer depend... 

Similar to the calculation of the cumulated amount of a species that has reacted, calculation of the total amount of heat produced during a dynamic experiment is useful to calculate yields and check elemental balances. 

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