2.10 Soaps and Detergents Soaps and enzyme-free detergents belong to a class of compounds called surfactants. They remove dirt and oil from our hands, clothes, and dinnerware, all with no chemi- cal reaction occurring in the process (i.e., no covalent bonds are broken or formed). Instead, the cleansing ability of soaps and detergents depends entirely on intermo- lecular interactions. The molecules specifically responsible for a soap's cleansing properties are typically salts of fatty acids, which are ionic compounds of the form RCO, Na* or RCO, K*. In these compounds, R is a long hydrocarbon chain, and the fatty acid salts generally contain from 12 to 18 carbons. Examples include potassium oleate and sodium palmitate: CH3 CH3 Na H2ha Sodium palmitate C16H3102NA Potassium oleate C18H3302K When a soap dissolves in water, it does so as its individual ions: the metal cation (Na* or K*) and the carboxylate anion (RCO,). Of these two species, the carboxylate anion is the one that is directly responsible for the soap's cleansing properties, because it has vastly different characteristics at its two ends (Fig. 2-26). Specifically:
Catalysis and Enzymatic Reactions
Catalysis is the kind of chemical reaction in which the rate (speed) of a reaction is enhanced by the catalyst which is not consumed during the process of reaction and afterward it is removed when the catalyst is not used to make up the impurity in the product. The enzymatic reaction is the reaction that is catalyzed via enzymes.
Lock And Key Model
The lock-and-key model is used to describe the catalytic enzyme activity, based on the interaction between enzyme and substrate. This model considers the lock as an enzyme and the key as a substrate to explain this model. The concept of how a unique distinct key only can have the access to open a particular lock resembles how the specific substrate can only fit into the particular active site of the enzyme. This is significant in understanding the intermolecular interaction between proteins and plays a vital role in drug interaction.
Recall from Section 2.10 that hard water ions like Ca2+ and Mg2- bind more strongly to the carboxylate groups in soap
than Na+ and K+ ions do. Why do you think this is so?
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