• Monday April 6,2020

Acids and Bases

We explain what acids and bases are, their characteristics, indicators and examples. In addition, what is the neutralization reaction.

Substances with pH less than 7 are acidic and those with pH greater than 7 are bases.
  1. What are acids and bases?

When we talk about acids and bases, we mean two types of chemical compounds, opposite in terms of their concentration of hydrogen ions, that is, their measure of acidity or alkalinity, their pH Their names come from the Latin acidus ( agrio ) and from the Arabic al-Qaly ( asizas ). The term bases is of recent use, formerly they were called lcalis.

Compounds with a pH less than 7.0 (equivalent to water or neutral term) are considered acidic . When the pH is lower, the degree of acidity is greater, with 0 being the gradient of hydrochloric acid. Those compounds with a pH greater than 7.0 are considered alkaline. The higher the pH the higher the degree of alkalinity or basic / alkaline pH, 14 being the gradient of caustic soda.

Both acids and bases are substances known to mankind for hundreds of years. However, it could only be fully understood with the formulation of atomic theory in the nineteenth century and the understanding of the subatomic aspects of chemistry.

As for its chemical structure, acids usually consist of hydrogen atoms attached to other organic and inorganic compounds (for example, hydrochloric acid is HCl). The bases are characterized by providing OH - ions to the medium, when in an aqueous solution, generally carrying (but not exclusively) in their formula a hydroxyl group.

In human industries, both types of compounds are used as catalysts for other reactions, or as reagents to obtain from them (or other substances) various desired elements, taking advantage of their reducing or caustic power.

Its use is common in the food, chemical, solvents, purifiers, medicines industry, in the manufacture of soaps or electric batteries.

It can serve you: pH

  1. Characteristics of acids and bases

Both acids and bases can exist as liquids, solids or gases, depending on their temperature. On the other hand, they can exist as pure or diluted substances, retaining many of their properties.

Obviously, the difference in pH is the most noticeable feature of each one, being in its most extreme variants a source of risks for organic matter and powerful catalysts for other reactions.

On the other hand, both acids and bases have different physical characteristics, such as:

Acids :

  • Sour taste, as evidenced by the acid present in various citrus fruits.
  • They are highly corrosive, being able to generate chemical burns on the skin, or respiratory damage when inhaling their gases.
  • Good conductors of electricity in aqueous solutions.
  • They react with metals producing salts and hydrogen.
  • They react with metal oxides to form salt and water.


  • They have a characteristic bitter taste.
  • Good conductors of electricity in aqueous solutions.
  • They are irritating to the skin, because they dissolve the skin fat, and can destroy organic matter by its caustic effect. Your breathing is also dangerous.
  • They have soapy touch.
  • They are soluble in water.
  1. Acids and bases in everyday life

The acid in the batteries creates a salt by reacting with the metals.

The presence of acids and bases in our daily life is abundant, even if we do not realize it. For example, inside the batteries of our electronic devices usually has sulfuric acid . So when they break down and pour their contents into the device, they react with the metal of the electrodes and create a whitish salt.

On the other hand, there are mild acids that we handle on a daily basis, such as acetic acid (vinegar), acetylsalicylic acid (aspirin), ascites acid (vitamin C ), the carbonic acid (present in carbonated soft drinks), the citric acid (present in citrus fruits), or the hydrochloric acid that our standard magician segregates to dissolve food, and we call sygos

As for the bases, sodium bicarbonate is used for baking, or as a deodorant, as well as in various heartburn remedies. Other common use bases are sodium carbonate (detergent), sodium hypochlorite (cleaning chlorine), magnesium hydroxide (laxative), and calcium hydroxide (building lime n).

  1. Acids and bases indicators

To distinguish between an acid and a base, as we have said, we must attend to the pH level. The best way to measure the pH is by litmus paper, usually in strips that can be dipped in the solution or supported by the compound, and observe the change in color they present.

Thus, the acids will change the color blue to pink, the orange from methyl to red, and in the case of phenolphthalene it leaves it colorless (or orange if it is a very strong acid) . The bases, on the other hand, change the red color of litmus paper to blue, and that of phenolphthalene to pink.

  1. Neutralization reaction

It is called neutralization or acid-base reaction to a chemical reaction that occurs when these two types of compounds are mixed, obtaining in return a salt and a certain amount of water. These reactions are usually exothermic (generate heat) and their name comes from the fact that the properties of both acid and base cancel each other out.

This reaction can occur in four ways, depending on the proportions of your reagents:

  • A strong acid and a strong base : the most abundant reagent will be dissolved in relation to the other.
  • A weak acid and a strong base : a basic pH solution will be obtained, since the base will remain in the reaction.
  • A strong acid and a weak base : the acid will be neutralized and an acid portion will remain in solution, depending on the degree of acid concentration.
  • A weak acid and a weak base : the result will be acidic or basic depending on the concentrations of its reagents.
  1. Examples of acids and bases

Some examples of acids and bases are:

Acids :

  • Hydrochloric acid (HCl)
  • Sulfuric Acid (H 2 SO 4 )
  • Nitric Acid (HNO 3 )
  • Perchloric acid (HClO 4 )
  • Formic acid (CH 2 O 2 )
  • Bromic acid (HBrO 3 )
  • Boric acid (H 3 BO 3 )
  • Acetic acid (C 2 H 4 O 2 )


  • Caustic Soda (NaOH)
  • Calcium hydroxide (CaOH)
  • Ammonia (NH 3 )
  • Baking Soda (NaHCO 3 )
  • Potassium Hydroxide (KOH)
  • Sodium Hypochlorite (NaClO)
  • Calcium fluoride (CaF 2 )
  • Barium hydroxide (Ba [OH] 2 )
  • Iron Hydroxide (Fe [OH] 3 )

Continue with: Chemical formula

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