Species amphoteric

In very general terms, petroleum is a mixture of (1) hydrocarbon types, (2) nitrogen compounds, (3) oxygen compounds, (4) sulfur compounds, and (5) metallic constituents. Petrolenm prodncts are less well defined in terms of heteroatom compounds and are better defined in terms of the hydrocarbon types present. However, this general definition is not adequate to describe the true composition as it relates to the behavior of the petroleum, and its products, in the environment. For example, the occnrrence of amphoteric species (i.e., compounds having a mixed acid-base natnre) is not always addressed, nor is the phenomenon of molecnlar size or the occnrrence of specific functional types that can play a major role in petrolenm behavior. 

H+X and Y+OH must be stable species in solution. Amphoteric species such as amino acids are retained on the suppressor column and, therefore. 

Table 4. Comparison of the Light Absorption Characteristics of the Amphoteric Species of Lumiflavin...

An amphoteric species can behave as either an acid or a base. In the preceding examples, we saw that water is an amphoteric species. It reacts as a base in the presence of HC1, but it reacts as an acid in the presence of bicarbonate. 

Monohydrogenphosphate is an important amphoteric species that helps maintain the pH balance in blood. That is, monohydrogenphosphate can act as either an acid or a base. 

An amphoteric species can behave as either an acid or a base. 

Definition of Acids and Bases 222 Conjugate Acid-Base Pairs 222 Amphoteric Species 224 Strong Acids 225 Strong Bases 225 Weak Acids 226 Weak Bases 226 Polyprotic Acids 227 Acid and Base Strength Ka and Kb 228 Acid/Base Strength of Conjugate Acid-Base Pairs 230 Acid-Base Reactions 231... 

Amphoteric species A compound that can accept both electron pairs and protons. 

Chapter 5 includes sufficient details on IEF to provide a better understanding of this technique. It also includes a number of applications of various proteins. Isoelectric focusing is applicable only to the fractionation of amphoteric species, such as proteins and peptides, that can act both as acids and bases. Nonamphoteric species, nucleic acids in particular, cannot be resolved by IEF. Both analytical and preparative modes of IEF, included in this chapter, have been developed as valuable tools for studying proteins. 

Acidity and basicity are relative properties. Many compounds are amphoteric and behave as acids or as bases according to a partner. Metal oxides are classified as acidic, amphoteric or basic. Experimentally, this classification corresponds to the adsorption of probe molecules[7, 8]. NH3 is a base probe molecule that reacts with the electron deficient metal atoms (Lewis acid) or the protons adsorbed on the hydrated surface, CO2 is usually considered as acidic and thus it is expected to adsorb more strongly on basic sites. According to this classification, Ti02 belongs to an amphoteric species and MgO to a basic species. A general difficulty for such classifications is that the order can vary with the choice of the probe. The Hard and Soft Bases and Acids theory[9, 10] responds to the necessity to refine the model with a second scale it is better to couple... 

Note that because this compound does have multiple basic functionalities, two ionization equilibria could be written for this amphoteric species. At mobile pH values between 3 and 5 the existence of multiple species is expected. Since the two pK values are close to one another 2pKa units apart), the inflection points overlap, making titration and/or chromatographic... 

The key to answering this question is to recognize that H2A is an amphoteric species It is both an acid,... 

III) Isoelectric focusing K Fractionation of amphoteric species on the basis of... 

A second situation in which an exact analysis of acid-base equilibrium is useful occurs when an amphoteric species is dissolved in water. The hydrogen carbonate ion (HCO3) is amphoteric because it can act as an acid in the equilibrium... 

Such a scheme indicates that the water molecule is decomposed in the process and, in addition, that the formation of an oxide usually requires basic conditions. However, in the preparation of oxides of amphoteric species such as Al(III) or Ga(III), acid hydrolysis could be employed. For example ... 

Fibre-included weighting agents can promote hydrolysis of the fibroin -e.g. over time tin salts are themselves hydrolysed to amphoteric species that can affect both acid and alkaline attack. 

What is an amphoteric species Name one and write balanced equations that show why it is amphoteric. 

Asphaltene Fractionation. Asphaltenes were separated into bases, acids, and neutral components by using a procedure described elsewhere (13). Following this initial separation, the basic fraction was then rechromatographed on a basic resin to produce a true basic fraction (nonadsorbed) and an amphoteric fraction (adsorbed). This procedure (Scheme II) allows asphaltenes to be separated into amphoteric species, bases, acids and neutral components. This type of separation was found to be a general feature of other asphaltenes separated from different bitumens, heavy oils, and conventional petroleum. 

Based on the Bronsted-Lowry definition of acids and bases, an acid is a proton donor and base is a proton acceptor. A species (charged or uncharged) that can gain or lose a proton is called amphoteric or amphiprotic species. For example, (bicarbonate ion) HCOj" can donate a proton acting as an acid. The same species can accept a proton acting as a base. Hence, amphoteric species can act as an acid or a base depending on the surrounding conditions. 

Conversely, the AN seale ean be viewed as a scale of hardness for adds since EtsPO is a hard reference base. Nevertheless, the merit of Gutmann s approach Kes in the fact that his scales provide both addic and basic parameters for amphoteric species, which is not the case with Drago s E and C classifications. 

It may happen that a given species is the oxidant in one couple and the reductant in another couple this case is similar to that of amphoteric species in acido-basic equilibria. 

Like other metal oxides and hydroxides, amphoteric species dissolve in acidic solutions because their anions, or OH , react with acids. What makes amphoteric oxides and hydroxides special, though, is that they also dissolve in strongly basic solutions. This behavior results from the formation of complex anions containing several (typically four) hydroxides bound to the metal ion (T Figure 17.21) ... 

I Mixtures of weak acids and bases I Amphoteric species... 

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