Acids and Bases in Industry

Chemists use whatever tools they can find in their laboratories to take full advantage of the properties of acids and bases. One tool they use is Kipp s apparatus, a piece of laboratory equipment that relies on acid-base chemistry to do its job. Named for its inventor, Dutch pharmacist Petrus Johannes Kipp (1808-1864), Kipp s apparatus (or gas generator) is especially useful for creating gases, such as carbon dioxide, hydrogen, or hydrogen sulfide, that the chemists can then use in other chemical reactions. 

Recall that (s) indicates a solid and (g) indicates a gas. Once gas production begins, a stoppered valve in the center bowl allows the chemist to control how much gas escapes. When the valve is opened, the gas can be collected. When it is closed, gas pressure 

To make hydrogen sulfide gas, pieces of iron(II) sulfide (instead of zinc) are placed in the center bowl of a Kipp s apparatus  

Some metals, such as iron, can form more than one type of ion. Iron ions can either have a +2 or a +3 charge. Chemists use Roman numerals to distinguish between the two different types of iron ions. The Roman numeral II in the name of the chemical compound iron(II) sulfide means that the iron ion in this compound has a +2 charge. 

Hydrogen sulfide gas is used in analytical chemistry laboratories to detect certain metal ions in a solution. If the solution contains a Group IIA metal, such as calcium, a precipitate will form when an acidic solution containing hydrogen sulfide is added to it. The precipitate forms because one of the products of the chemical reaction is insoluble (which means it does not dissolve). 

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The importance of acids and bases in industrial processes is almost impossible to overstate. Correct pH conditions are often essential to the progress of manufacturing reactions. At the same time, it may be highly undesirable for the product to contain excessive acid or base. In the food and petroleum... 

We have seen that the value of an equilibrium constant tells us whether we can expect a high or low concentration of product at equilibrium. The constant also allows us to predict the spontaneous direction of reaction in a reaction mixture of any composition. In the following three sections, we see how to express the equilibrium constant in terms of molar concentrations of gases as well as partial pressures and how to predict the equilibrium composition of a reaction mixture, given the value of the equilibrium constant for the reaction. Such information is critical to the success of many industrial processes and is fundamental to the discussion of acids and bases in the following chapters. 

Titration is one of the universal techniques of chemistry and is commonly used to determine the concentration of a solute. Titrations may be either acid-base titrations, in which an acid reacts with a base, or redox titrations, in which the reaction is between a reducing agent and an oxidizing agent. Here we concentrate on acid-base titrations. The technique is used in research laboratories, hospitals, and industry to determine the amounts of acid and base in solutions. It is also used in forensic laboratories and for monitoring the environment. 

Many acids and bases are industrial and household substances ( FIGURE 4.5), and some are important components of biological fluids. Hydrochloric acid, for example, is an important industrial chemical and the main constituent of gastric juice in your stomach. Acids and bases are also common electrolytes. 

In this chapter you will learn that the danger associated with acids and bases is a function of their concentration and identity. Most acids and bases are not inherently dangerous. They are all around us. The acid-base balance in our blood is critical to good health and many biological reactions depend on acids and bases in the body. The acid content of our rainfall (and other forms of precipitation) has a critical role in determining the health of our rivers and forests and our ability to raise the foodstuffs upon which we depend. Acids and bases are key components of many manufacturing processes. In fact, sulfuric acid is required by so many industrial processes that the amount of it sold each year is taken as a measure of a nation s economy. 

Smiechowski and Lvovich monitored the levels of acidity and basicity in industrial lubricant. The sensor was based on electrochemical impedance methodology. An iridium oxide potentiometric sensor was developed in both a conventional and MEMS configuration. Tests of the sensors in diesel lubricant showed good correlation between TAN, TEN, and the voltage output of each sensor [7]. Widera et al. used a potentiometric iridium oxide electrode as an indicating electrode with a silver/silver chloride reference electrode for the off-line monitoring of fuel acidity. The data showed that the iridium oxide sensor responds to compounds present in fuel that have acid-base character and it is possible to determine the acidity of different fuels and discriminate between unstressed and thermally stressed fuels. Experimental results indicated the ability to correlate the response of the iridium oxide sensor with the total acid numbers of different fuels [20]. 

Table III summarizes the parameters that affect Brrfnsted acid-catalyzed surface reactions. The range of reaction conditions investigated varies widely, from extreme dehydration at high temperatures in studies on the use of clay minerals as industrial catalysts, to fully saturated at ambient temperatures. Table IV lists reactions that have been shown or suggested to be promoted by Br nsted acidity of clay mineral surfaces along with representative examples. Studies have been concerned with the hydrolysis of organophosphate pesticides (70-72), triazines (73), or chemicals which specifically probe neutral, acid-, and base-catalyzed hydrolysis (74). Other reactions have been studied in the context of diagenesis or catagenesis of biological markers (22-24) or of chemical synthesis using clays as the catalysts (34, 36). Mechanistic interpretations of such reactions can be found in the comprehensive review by Solomon and Hawthorne (37).

Titrations in non-aqueous solvents have been traditionally an important tool for the accurate determination of various pharmaceuticals, some acids in foods, use of some acids or bases in detergents, cosmetics and textile auxiharies, in the analysis of industrial process streams, the analysis of polymers [1-7]. The determination of the pK or pK values of organic compoimds with acidity or basicity constant less than 10 can only be reahsed in non-aqueous media. Although water has excellent solvent properties, it is not suitable for such organic compotmds since the pH jump at the equivalence point in aqueous solution carmot be evalrrated with reasonable accuracy, with this resrrlt, the end point carmot be found. Moreover, most of this compotmds ate not soluble in water. For these reasons, titration in non-aqueous media has recently acqttired great importance. It is now well known that non-aqueous titrations greatly depend on the solvents used [4, 8-13]. 

Two of the most important classes of chemical compounds are acids and bases. A small sampling of acids and bases found around the home demonstrates their importance in daily life. A few of these include fruit juice, aspirin, milk, ammonia, baking soda, vinegar, and soap. Beyond their presence in numerous household items, acids and bases are key ingredients in the chemical process industry. More sulfuric acid is produced than any other chemical in the United States with an annual production of 40 million tons. While the commercial applications of acids and bases illustrate their importance in everyday life, on a more fundamental level each one of us inherited our characteristics and genetic make-up through the acid DNA, deoxyribonucleic acid. 

Since NR is non-polar, its vulcanizates can swell to several times their original volume in non-polar solvents such as mineral oils, toluene, gasoline and diesel oil. It has good resistance to polar fluids such as mild acids and bases typically encountered in the mineral and chemical processing industries. The compression set resistance... 

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