Various acids and bases Arrhenius

Introduction

It was in the year 1887 that the Swedish scientist Svante Arrhenius made the first public presentation of his Arrhenius theory. To conduct electricity, one must have ions that are free to move around. Svante Arrhenius observed that an acid solution conducts electricity by dissolving the substance in the solution, which then dissociates into ions. This was the first observation of its kind. This concept is well-known today, but it was controversial at the time it was first introduced. “Electrolytic dissociation” is the term used to describe this theory.

Water is a non-conducting substance, meaning it does not carry electricity. It conducts electricity by dissolving a substance in water and allowing it to conduct electricity. The substances in question are referred to as electrolytes, and the process is referred to as “Electrolytic dissociation.”

Arrhenius Theory of Acid and Base

The acid-base theory states that when a substance dissolves in aqueous solution, it releases an ion called the hydrogen ion (H+). It has the effect of increasing the concentration of H+ ions in a solution. In aqueous solutions, the base is a substance that ionises the OH– ion by dissolving in the solution. The concentration of OH- ions in the solution is extremely high.

The general properties of acid are: 

• Acidic in nature
• The concentration of H+ ion is high
• Taste Sour
• Are red on blue litmus paper
• Have PH<7
• Common examples: Lemons, oranges, vinegar, urine, sulphuric acid, hydrochloric acid

The general properties of bases are: 

• Basic in nature
• The concentration of OH– ion is high
• Taste bitter
• Are blue on red litmus paper
• Have PH>7
• Common examples: Soap, toothpaste, bleach, cleaning agents, limewater, ammonia, water, sodium hydroxide

Ions of hydrogen or ions of hydronium?

Consider the following scenario: we prepared a 2M aqueous solution of hydrobromic acid, HBr, which is an Arrhenius acid, and tested it. Is it correct to say that we have 2M of H+ ions present in our solution?

No, not at all. In practise, the positively charged protons react with the surrounding water molecules to form hydronium ions, H3O+.

Arrhenius Acid

The presence of Arrhenius acid in an aqueous solution raises the concentration of protons or hydrogen ions in the solution. Consider the presence of hydrochloric acid in water. As explained further below, HCl undergoes a dissociation reaction, resulting in the formation of the ions H+ and Cl–. The concentration of H+ ions is increased as a result of the formation of the hydronium ion.

HCl (aq) → H+(aq) + Cl–(aq)

HCl (aq) + H2O(l) → H3O+(aq) + Cl–(aq)

Other examples of Arrhenius acids are listed below

NHO3(aq) + H2O(l) → H3O+(aq) + No3–

In this reaction, nitric acid dissolves in aqueous water to give hydrogen and nitrate ions.

Arrhenius Acids

Hydrochloric acid (HCl)

Nitric acid (HNO3)

Sulphuric acid (H2SO4)

Arrhenius Base

It is a substrate that increases the concentration of hydroxide ions in aqueous solution, and it is also known as an Arrhenius base. As an example of an Arrhenius base, sodium hydroxide compound in water is highly soluble and dissociates to give sodium ion and hydroxide ion when exposed to light.

Sodium hydroxide completely dissolves in water to form hydroxide ion and sodium ion. This results in an increase in the concentration of hydroxide ions in the solution.

NaOH(aq) → Na+(aq) + OH–(aq)

Examples of an Arrhenius base are listed below

Sodium hydroxide NaOH

Potassium hydroxide KOH

Calcium hydroxide Ca(OH)2

Limitations of Arrhenius theory

It is only in aqueous solution that the Arrhenius theory is applicable; for example, according to the theory, HCl is an acid in aqueous solution but not in benzene, despite the fact that it donates H+ ions to the benzene. According to Arrhenius’ definition, the solution of sodium amide in liquid ammonia is not alkaline, despite the fact that deprotonating ammonia is caused by the amide ion.

Conclusion:

When it comes to acids and bases, according to Arrhenius’s theory of acid-base, acids are those that readily dissociate in water to release hydrogen ions. Alkaline species dissolve in aqueous solution to form hydroxide ions, which are toxic. The term “Arrhenius acid” refers to any species that raises the concentration of hydrogen ions in aqueous solution. An Arrhenius base is any species that increases the concentration of OH- in an aqueous solution by an Arrhenius factor. In an aqueous solution, hydrogen ions (H+) react immediately with water molecules to form hydronium ions (H3O+), which are toxic. The reaction of an Arrhenius acid and base usually results in the formation of water and a salt in an acid-base or neutralisation reaction.