Baking, acid-base reactions

The evolution of caibon dioxide essentially follows the stoichiometiy of acid—base reactions. Baking soda determines the amount of carbon dioxide evolved, whereas the type of acid controls the speed of hberation. The reaction equations for some acids with baking soda ate as follows ... 

In acid-based reactions 2-acetyl-3-hydroxyfuran (isomaltol) (5.76), 3-hydroxy-2-methylpyran-4-one (5.77), and maltol (5.79) are formed. They are responsible for the baked bread aroma. 

Do you remember how much fun it was to watch a vinegar baking soda volcano erupt The bubbles of carbon dioxide (CO2) resulted from a decomposition reaction that quickly followed the acid-base reaction between the vinegar (HC2H3O2), an acid, and baking soda (NaHCOs), a base, as shown below. Acid-Base Reaction... 

Similar to inorganic acids, the reaction of carboxylic acids and bases produces carboxylic acid salts. Several of these salts are commonly used in foods and beverages as preservatives. The most common are salts from benzoic, propionic, and sorbic acids. The salts of these acids have names ending with ate, and can often be found in the list of ingredients of baked goods and fruit drinks. Several common preservatives are shown in Figure 15.11. 

These reactions are also acid-base interactions. One of these that may immediately come to mind in this category is a reaction that you more than likely did as a child—mixing vinegar and baking soda. Now that you are an AP Chemistry student, you know that you were really mixing acetic acid, HC2H302, and sodium bicarbonate, NaHC03. When these two substances are mixed, the reaction proceeds as follows ... 

Metal acetates can also be prepared from acetic acid and an appropriate base, as in the popular "baking soda + vinegar" reaction ... 

Figure 4.1 In a soda-acid fire extinguisher, a chemical reaction between an acid (sulfuric acid) and a base (baking soda) produces a jet of water that can put out certain kinds of fires.

A tetracarboxylated derivative was prepared recently by reaction of a commercial reactive dye with two molar equivalents of aspartic acid. This novel derivative was evaluated by pad-dry-bake and pad-batch-bake methods under slightly acidic conditions in the presence of cyanamide as activator [49]. An interesting disperse dye containing a novel reactive anhydride system (7.54) was prepared from the parent dye carboxylate (7.53) by reaction with ethyl chloroformate in the presence of a tertiary base (Scheme 7.32). Such dyes will... 

The reaction between baking soda and an acid can easily be seen. Put a teaspoon of baking soda in a dish, add a teaspoon of vinegar, and watch it bubble. The baking soda is a base. The vinegar is an acid. The bubbling comes from the carbon dioxide gas created by the reaction. The solution that is left over is neutral. 

There are many different acids and bases. Being able to predict the results of reactions between them is important. Bakers, for example, depend on neutralization reactions to create light, fluffy baked goods. Gardeners and farmers depend on these reactions to modify the characteristics of the soil. Industrial chemists rely on these reactions to produce the raw materials that are used to make a wide variety of chemicals and chemical products. (See Figure 10.13.)... 

If a small quantity of an acid or a base is spilled in a laboratory, you can use a neutralization reaction to minimize the hazard. To neutralize a basic solution spill, you can add solid sodium hydrogen sulfate or citric acid. For an acidic solution spill, you can use sodium hydrogen carbonate (baking soda). Note that you cannot use a strong acid or base to clean up a spill. This would result in another hazardous spill. As well, the neutralization reaction would generate a lot of heat, and thus produce a very hot solution. 

As discussed previously, neutralization is the process by which an acid is reacted with a base to form a salt and water. The general reaction for this process can be simplified by showing how the H1+ and OH1- ions combine to form water. Perhaps you have seen a commercial on TV where an antacid promises to neutralize more acid than another antacid. Perhaps you have seen a situation in the laboratory where an acid was spilled. The laboratory specialist should have neutralized the spill with baking soda. These are situations where the amounts of acid and base being neutralized are not completely measured out. There is a process where acids and bases can be measured out in exact quantities so that they neutralize each other exactly and do so without any excess acid or base. This process is called a titration. 

Weak acids and bases will also undergo neutralization reactions. The reaction of the acetic acid (HAc) in vinegar with the sodium bicarbonate (NaHCOs) in baking soda produces water, sodium ions (Na+), acetate ions (Ac), and carbon dioxide gas (CO2). The reaction between baking soda and acids in dough creates bubbles of carbon dioxide that make cakes and cookies rise and become fluffy. 

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