Acids and Bases

Published on May 30, 2016


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At the very general level of consideration, that is, when deliberating upon the name of the substance itself without considering anything else, acids are chemical substances which are sour in taste. Bases, on the other hand, are thought to have a bitter taste. However, this definition is quite crude and not an exact or even a correct one since there are many substances which are sour tasting but they are not acids. Also, there are many acids which do not taste sour. How does one go about classifying substances as acids and bases then?

Definition of acids and bases

There are different perspectives on what is actually an acid and a base. Throughout the years, different scientists have proposed different ways to define them.  Almost all of these are related to the exchange of something between an acid or base and the solvent in which it is dissolved. Adopting a very broad perspective, acids are substances which furnish hydrogen or donate them and bases are substances which accept the hydrogen.

Lewis acids and bases

However, it is not necessary that hydrogen should be involved. According to the Lewis theory of acids and bases, an acid is concerned with accepting electrons from a generous donor, which is the part usually played by a base. One thing is quite clear about the nature of acids and bases: a substance when acting as an acid causes some other substance it is interacting with to act as a base and vice- versa.

Measuring up an acid or base

An acid and a base has a particular strength which is defined by the tendency for it to actually act as an acid or base by satisfying one of the various definitions. For example, the higher the acid strength, the more tendencies it has to furnish hydrogen in the solution. Also, the higher the strength of an acid or base, the more unstable it is and, hence, more reactive. An acid of sufficiently high strength can cause a rapid reaction as it is uncomfortable in its unstable state. It has a very strong tendency and a strong urge to release hydrogen when dissolved in the solution and relieve itself.

pH scale

Scientists have developed a scale called the pH scale to measure the strength of acids and bases. The scale varies from 0 to 14, which are the values of pH of the substance on hand. Neutral substances, which are neither acid nor base and lie in the middle of the spectrum, have pH value of 7. Acids occupy the lower pH values’ domain and bases occupy the higher pH values’ domain. An acid of very high strength will have a pH equal to zero. Similarly, a strong base on the other extreme will have a pH value of 14 associated with it.

Titration: dropping the base (or acid)

Titration is a quantitative technique commonly used to determine the concentration of an acid or base. Concentration is concerned with the amount of the acidic or basic substance that is present in the solution. It is different from the strength of the acid or base. During titration, neutralization reaction takes place between acid and base. Neutralization can be considered as a reaction which nullifies the effects of the acid and the base involved, unless they are of highly unmatched strengths.

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