We explain what acids and bases are, their properties, indicators, and examples. Also, what is the neutralization reaction?
Acids and bases Definition
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 (“sour”) and from the Arabic al-QALY (“ashes”). The term ” bases ” is of recent use, formerly they were called alkalis.
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.
In terms of chemical structure, the acids typically consist of hydrogen atoms bonded to other compounds organic and inorganic (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.
Properties 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:
Properties of 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.
Properties of Bases:
- They have a characteristic bitter taste.
- Good conductors of electricity in aqueous solutions.
- They are irritating to the skin, as they dissolve the skin fat, and can destroy organic matter by their caustic effect. Your breathing is also dangerous.
- They have soapy touch.
- They are soluble in water.
Uses of Acids and bases in everyday life
The presence of acids and bases in our daily life is abundant, even if we don’t realize it. For example, inside the batteries of our electronic devices there is usually 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 daily , such as acetic acid (vinegar), acetylsalicylic acid (aspirin), ascorbic acid (vitamin C), carbonic acid (present in carbonated soft drinks), citric acid (present in citrus fruits), or the hydrochloric acid that our stomach secretes to dissolve food, and what we call “gastric juices.”
As for the bases, sodium bicarbonate is used for baking, or as a deodorant , as well as in various heartburn remedies. Other commonly used bases are sodium carbonate (detergent), sodium hypochlorite (cleaning chlorine), magnesium hydroxide (laxative), and calcium hydroxide (building lime).
Acid and base 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 phenolphthalein, 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 phenolphthalein to pink.
See Also: Types of Indicators
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:
- 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.
- 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.
Acids and bases Examples
Some examples of acids and bases are:
Examples of 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 )
Examples of Bases
- 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 )