Acids, bases and salts

Lemons and limes are examples of Ibod which contains acidic solutions. 

1 Acids and Bases 15.6 Dissociation and Ionization 15.11 Writing Net Ionic Equations 

3 Reactions of Bases 15.7 Strong and Weak Electrofytes 15.13 Colloids 

5 Electrolytes and Nonelectrofytes 15.9 Introduction to pH 15.10 Neutralization 15.15 Applications of Colloidal Properties 

Acids are important chemicals. They are used in cooking to produce the surprise of tartness (from lemons) and to release CO2 bubbles from leavening agents in baking. Vitamin C is an acid that is an essential nutrient in our diet. Our stomachs release acid to aid in digestion. Excess stomach acid can produce heartburn and indigestion. Bacteria in our mouths produce acids that can dissolve tooth enamel to form cavities. In our recreational activities we 

15 ACIDS, BASES, AND SALTS Inorganic substances can be classified into three important groups acids, bases, and salts. 

An acid is most simply defined as a substance which, when dissolved in water, undergoes dissociation with the formation of hydrogen ions as the only positive ions. Some acids and their dissociation products are as follows  

Actually, hydrogen ions (protons) do not exist in aqueous solutions. Each proton combines with one water molecule by coordination with a free pair of electrons on the oxygen of water, and hydronium ions are formed  

The existence of hydronium ions, both in solutions and in the solid state has been proved by modem experimental methods. The above dissociation reactions should therefore be expressed as the reaction of the acids with water  

For the sake of simplicity however we shall denote the hydronium ion by H+ and call it hydrogen ion in the present text. 

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The most chemical-resistant plastic commercially available today is tetrafluoroethylene or TFE (Teflon). This thermoplastic is practically unaffected by all alkahes and acids except fluorine and chlorine gas at elevated temperatures and molten metals. It retains its properties up to 260°C (500°F). Chlorotrifluoroethylene or CTFE (Kel-F, Plaskon) also possesses excellent corrosion resistance to almost all acids and alkalies up to 180°C (350°F). A Teflon derivative has been developed from the copolymerization of tetrafluoroethylene and hexafluoropropylene. This resin, FEP, has similar properties to TFE except that it is not recommended for continuous exposures at temperatures above 200°C (400°F). Also, FEP can be extruded on conventional extrusion equipment, while TFE parts must be made by comphcated powder-metallurgy techniques. Another version is poly-vinylidene fluoride, or PVF2 (Kynar), which has excellent resistance to alkahes and acids to 150°C (300°F). It can be extruded. A more recent development is a copolymer of CTFE and ethylene (Halar). This material has excellent resistance to strong inorganic acids, bases, and salts up to 150°C. It also can be extruded. 

There are two philosophies regarding how to best slow a runaway reaction. One view holds that simple water deluge is the best method as it provides immediate cooling and dilution. The anti position is that the batch should be deluged and neutralized simultaneously. Kumpinsky reports that minimum self-heat rates occur between pH 4 and 7 [78]. Since neutralization involves production of additional heat, because the pH of a runaway batch is rarely known, and since the phenolic reactions are catalyzed by acid, base, and salt it seems likely that simple deluge is the surest method. 

The US Bureau of Mines found the chemical and galvanic corrosion behaviour of both the TZM and Mo-30W alloy to be generally equal or superior to that of unalloyed molybdenum in many aqueous solutions of acids, bases and salts. Notable exceptions occurred in 6-1 % nitric acid where both alloys corroded appreciably faster than molybdenum. In mercuric chloride solutions the TZM alloy was susceptible to a type of crevice corrosion which was not due to differential aeration. The alloys were usually not adversely affected by contact with dissimilar metals in galvanic couple experiments, but the dissimilar metals sometimes corroded galvanically. Both alloys were resistant to synthetic sea water spray at 60°C. 

The rest of this chapter is a variation on a theme introduced in Chapter 9 the use of equilibrium constants to calculate the equilibrium composition of solutions of acids, bases, and salts. We shall see how to predict the pH of solutions of weak acids and bases and how to calculate the extent of deprotonation of a weak acid and the extent of protonation of a weak base. We shall also see how to calculate the pH of a solution of a salt in which the cation or anion of the salt may itself be a weak acid or base. 

The electrical conductivity detector is probably the second most commonly used in LC. By its nature, it can only detect those substances that ionize and, consequently, is used frequently in the analysis of inorganic acids, bases and salts. It has also found particular use in the detection of those ionic materials that are frequently required in environmental studies and in biotechnology applications. The detection system is the simplest of all the detectors and consists only of two electrodes situated in a suitable detector cell. An example of an electrical conductivity detector sensing cell is shown in figure 13. 

Seven chemical reactions were identified from the chemistry syllabus. These chemical reactions were selected because they were frequently encountered during the 2-year chemistiy course and based on their importance in understanding concepts associated with three topics, namely, acids, bases and salts, metal reactivity series and inorganic chemistry qualitative analysis. The seven types of chemical reactions were combustion of reactive metals in air, chemical reactions between dilute acids and reactive metals, neutralisation reactions between strong acids and strong alkalis, neutralisation reactions between dilute acids and metal oxides, chemical reactions between dilute acids and metal carbonates, ionic precipitation reactions and metal ion displacement reactions. Although two of the chemical reactions involved oxidation and reduction, it was decided not to include the concept of redox in this study as students had only recently been introduced to ion-electron... 

The cement-forming reaction is a special case of an acid-base reaction so that concepts of acid, base and salt are central to the topic. In AB cement theory, we are concerned with the nature of the acid-base reaction and how the acidity and basicity of the reactants are affected by their constitution. Thus, it is appropriate at this stage to discuss the various definitions and theories available. 

Cady, H. P. Elsey, H. M. (1922). A general conception of acids, bases and salts. Science, 56, 27 (Lecture abstract). 

Franklin, E. C. (1924). Systems of acids, bases and salts. Journal of the American Chemical Society, 46, 2137-51. 

Aqueous solutions of acids, bases, and salts are the ionic conductors used most widely and studied most thoroughly. The importance of other types of ionic conductors has increased in recent times, but aqueous solutions are still preeminent. Their significance goes far beyond electrochemistry as such they can be found in practically all spheres of human activity. They are of exceptional importance in the... 

Acids, bases, and salts (i.e., electrolytes in the second sense of the word) dissociate into ions when dissolved in water (or in other solvents). This dissociation can be complete or partial. The fraction of the original molecules that have dissociated is known as the degree of dissociation, a. Substances that exhibit a low degree of dissociation in solution are called weak electrolytes, whereas when the value of a comes close to unity we speak of strong electrolytes. 

Under the aforementioned circumstances, the two-step reaction 4.53 and the associated eqns. 4.54-4.62 are equally valid on the understanding that HS represents Hcres, etc. further, it must be realized that during titration various amounts of HX and B are simultaneously present. Therefore, from previous measurement of the conductivities (k) of dilution series of the separate acids, bases and salts in m-cresol, the overall constants KHX, KB and KBH+X were calculated by the Fuoss and Kraus method66,67 (with the use of e = 12.5 and viscosity = 0.208 P for m-cresol). For C6H6S03H and HC1 it was necessary to calculate the equivalent conductivity at zero concentration from the equation... 

Ionization is the process of separation or dissociation of a molecule into particles of opposite electrical charge (ions). The presence and extent of ionization has a large effect on the chemical behavior of a substance. An acid or base that is extensively ionized may have markedly different solubility, sorption, toxicity, and biological characteristics than the corresponding neutral compound. Inorganic and organic acids, bases, and salts may be ionized under environmental conditions. A weak acid HA will ionize to some extent in water according to the reaction ... 

Peiffer, D.G., Lundberg, R.D., and Turner, S.R. "Intramolecular Polymeric Complexes viscosifiers for Acid, Base and Salt (Aqueous) Solutions," US Patent 4,461,884(1984). 

Reactions in Aqueous Solutions I Acids, Bases, and Salts... 

PMMA is resistant to nonoxidizing acids, bases, and salts at ordinary temperatures but is attacked by oxidizing acids at room temperature. It is resistant to highly polar solvents, such as ethanol, but is soluble in less polar solvents, such as toluene. 

When Boyle began his scientific work, chemistry was not yet a science. The complexity of the materials with which chemists worked made generalizations about their behavior difficult. There was no standard chemical terminology and no concept of chemical purity. Paracelsus had tried to use chemical preparations that were as pure as possible but most who succeeded him didn t bother. No distinction was made between organic and inorganic substances, and there was no clear understanding of the difference between acids, bases, and salts. 

Inorganic acids, bases, and salts with pH values <4 and >9 are not compatible with aluminum. Pitting corrosion of aluminum can occur when it comes in contact with salt water and copper halide salts. 

It is a system of acids, bases and salts with liquid ammonia as solvent instead of water. Thus the water system ... 

In this first part, also, Lavoisier considers the subjects of oxidation, fermentation, putrefaction, the composition of air and water and of acids, bases, and salts in general. 

In summary, the chemistry of ammonia solutions is remarkably parallel to that of aqueous solutions. The principal differences are in the increased basicity of ammonia and its reduced dielectric constant. The latter not only reduces the solubility of iotuc materials, it promotes the formation of ion pairs and ion clusters. Hence even strong acids, bases, and salts are highly associated. 

Inorganic compounds also may be classified as acids, bases, and salts. This classification is particularly useful as a basis for naming the chemicals with which we shall deal. 

Since in the interconversion of electrical and chemical energies, electrical energy flows to or from the system in which chemical changes lake place, it is essential that the system be. in large part, conducting or consist of electrical conductors. These are of two general types—electronic and electrolytic—though some materials exhibit both types of conduction. Metals are the most common electronic conductors. Typical electrolytic conductors are molten salts and solutions of acids, bases, and salts. 

A broader definition than that confined to solutions is demanded in some fields of chemistry (e.g., in high temperature reactions of acids, bases, and salts). In the foimation of metallulgical slags, at furnace tempeiatuies, calcium oxide is used as base and silicon oxide and aluminum oxide as acids calcium aluminosilicate is produced as a fused salt. Sodium carbonate and silicon oxide when fused react to form the salt sodium silicate with the evolution of carbon dioxide. In this sense ... 

Acids, bases, and salts.—To distinguish between the ordinary oxygen salts, acids, and bases and those compounds which bear an analogous relation to ammonia, E. C. Franklin applies the term hydro-salts, hydro-acids, and hydro-bases to those compounds which are related to water, like the ammono-salts, ammom-acids, and ammono-bases are related to the corresponding ammonia derivative. The terms... 

Figure 6.49 Acid, base, and salt inhibition of simple carbon dioxide hydrates.

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