Acids in Chemistry

Acids in chemistry are defined as hydrogen-containing substances that give hydrogen ions (H+) in a water solution. An acid is sour in taste and changes the colour of blue litmus to red. Acids can also change the colour of the indicators (phenolphthalein, methyl orange, etc) when added to it. They react with metals like iron, zinc, and aluminum to liberate hydrogen.

Acid properties, neutralizer, definition, theory in chemistry, natural sources and examples of acids and bases with practice problems

Most of the chemical compounds have some acidic or basic properties. Strong acids are neutralized by certain types of strong bases to form salts and water. Most of the digestive fluids of humans and animals show some acidic components. For example, HCl present in the stomach helps in the digestion of food.

Hydrochloric acid (HCl), sulfuric acid (H2SO4), formic acid (HCOOH), acetic acid (CH3COOH), and nitric acid are the most common examples that we use widely in the chemical laboratory and various industries.

They also occur in some naturally occurring fruits such as mango, lemon, orange, tamarind, tomato, etc. Examples of some naturally occurring acids and their sources are given below in the table:

Natural Source Acid Chemical Formula
Vinegar Acetic acid CH3COOH
Orange and Lemon Citric acid C6H6O7
Tamarind Tartaric acid C4H6O6
Tomato Oxalic acid C2H2O4
Curd Lactic acid C3H6O3
Ant sting or bite Methanoic acid or formic acid HCOOH
Apple Malic acid C4H6O5

Theories of Acids and Bases

Arrhenius’s definition of acids and bases is limited to aqueous solutions only. However, modern acid-base theories are not only limited to aqueous or water solutions.

Today, these theories can used to define acids and bases in aqueous and non-aqueous solutions or even in a free state. The modern concepts or theories are:

  • Solvent System Concept
  • Brønsted–Lowry Theory
  • Lewis Theory
  • Hard Soft Acid-Base (HSAB) Theory

In this part of learning chemistry, we study definitions and acidic and basic properties by different concepts or theories. The various chemistry articles and topics related to acids and bases definitions, properties, indicators, reactions, and practice problems are given below:

Acid base titration process in chemistry

Acid Base Titration

What is Acid Base Titration? Acid base titration in chemistry is an experimental procedure used to calculate the unknown concentration of an acid or base...
Hydrochloric acid or muriatic acid or aqueous solution of hydrogen chloride gas chemical formula HCl and structure with properties and uses

Hydrochloric Acid

What is Hydrochloric Acid? Hydrochloric acid or muriatic acid is an aqueous solution of hydrogen chloride gas with the chemical formula HCl. It was historically...
Buffer solution definition, uses, pH, and types of acid and alkali buffers solutions in chemistry and biolog


What is a Buffer Solution in Chemistry? Buffer solution or simply called buffer in analytical chemistry or biology is a solution whose pH remains virtually...
Nitric acid (chemical formula HNO3) and nitrate ion structure, uses, and production process

Nitric Acid

What is Nitric Acid? Nitric acid (chemical formula HNO3) is colorless, fuming, highly corrosive liquid. It is the most important heavy chemical used in the...
Boric acid (H3BO3) Structure, Properties, Preparation, and Chemical uses

Boric Acid

What is Boric Acid? Boric acid or Boric Powder, also called hydrogen borate or orthoboric acid is a white crystalline solid with the chemical formula...
Sulfuric acid (H2SO4) and sulfate ion structure. production, properties and uses

Sulfuric Acid

Sulfuric acid chemical formula Sulfuric acid or sulphuric acid or hydrogen sulfate (chemical formula H2SO4) is a commercially important dense, colorless, oily, corrosive liquid. It...
Definitions, Examples and Chemical Properties of Hard, Soft and Borderline Acids

Hard Soft Acid Base

Hard Soft Acid Base Theory Hard soft acid base theory or HSAB principle was proposed by Ralph Pearson in 1963. It is very helpful for predicting...
pH and pOH Scale chart and definition for acidic, neutral and basic solution in chemistry

pH Scale

What is pH and pOH? pH and pOH scale define and measure the acidity and basicity of neutral, acidic, and basic solutions in water based...
Acids and bases properties and definition in chemistry

Acids Bases

Acids and bases properties Acids and bases in chemistry commonly possess some opposite properties. For example, acids are chemical substances whose aqueous or water solution...
Definition and Chemical Properties of Lewis Acids Base Reaction

Lewis Acids Bases

Lewis acid and base definition Lewis acid base concept or theory explains the acids and bases properties in terms of electronic structure with the formation of...