What Is the Definition of a Traditional Acid & Base?
Often encountered in everyday life and chemistry, acids and bases are complete opposites, and have the ability to neutralize each other. Human bodies, for example, contain acids and bases that are regulated by the lungs, blood and kidneys in a highly sophisticated equilibrium process. Understanding the definition of acids and bases increases understanding about the chemical properties and reactions between things encountered on a regular basis.
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Definitions
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Traditional acids are defined, according to Svante Arrhenius, a famous Swedish chemist, as producers of positively charged hydrogen ions when added to water. Bases, on the other hand, are producers of negatively charged hydroxide ions when added to water. However, according to elmhurst.edu, the above definition is too simple. In 1923, a new definition was introduced, called the Bronsted-Lowery definition. This definition argues that acids are proton donors that donate its positive charge when they react with a bases, and bases are a proton receptors that receive a positive charge when they react with an acid. In other words, acids lose their hydrogen ions and bases gain hydrogen ions when the two are mixed. Furthermore, according to this definition, to determine what's a base and what's an acid, just count the hydrogen ions before and after a chemical reaction.
Properties
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Several observation properties help distinguish acids from bases. Acids taste sour, for example, while bases are bitter. Bases feel slimy or slippery to the touch, and acids will burn the skin or sting if splashed onto an open wound. Furthermore, if litmus paper is dipped into an acid, it will turn red, whereas it will turn blue if dipped into a base. Alternatively, if phenolphthalein is mixed into an acid, it will remain colorless, but it will turn a bright pink if mixed into a base. Acids are further distinguished by their reaction with metal. Such a reaction produces hydrogen gas, and carbonates or bicarbonates, which produces carbon dioxide gas.
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PH
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A substances acidity and baseness is determined by the pH scale. The scale ranges from zero to 14. Anything that is less than 7 is considered acidic, while anything that is higher than 7 is considered basic. A substance is deemed neutral if it has a pH of seven. Every whole pH value below seven is 10 times more acidic, and every whole value above seven is 10 times more basic. A pH of three, for instance, is 10 times more acidic than a pH of four. Alternatively, a pH of 11 is 10 times more basic than a pH of 10.
Strong and Weak Acids and Bases
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Strong acids completely dissociate in water, splitting into positively charged hydrogen ions. In other words, when a strong acid dissociates, only one complete positively charged hydrogen ion is separated. Only six strong acids exist: hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric (HNO3), perchloric acid (HClO4), hydrobromic acid (HBr), hydroiodic acid (HI). All other acids are considered weak. Weak acids only partially dissociate in water. Strong bases completely dissociate into cations, splitting into negatively charged hydroxide ions. Weak bases bases are actually negatively charged ions of weak acids. Also, weak bases don't dissociate into negatively charged hydroxide ion, but furnish negatively charged hydroxide ions when mixed with water.
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References
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