Properties of Bases: Overview, Questions, Preparation

This chapter has multiple topics listed below:

Acids, Bases and Salts Acid Strength Difference between Acid and Bas...Examples of Bases Zinc carbonate Zinc Nitrate Aluminium Phosphate Aspartic Acid Butyric Acid Tannic acid Uses of Folic Acid Uses of Acetic Acid Lactic Acid formula Uses of Citric Acid Magnesium Nitrate Barium Iodide Dilute Acids Magnesium Phosphate Uses of Hydrochloric Acid List of Strong Acids Butanoic Acid Sodium Chlorate Barium Carbonate Chloroacetic Acid Magnesium Bicarbonate Red Cabbage Indicator Sodium Hexametaphosphate Zinc Hydroxide Potassium Iodate Peroxydisulfuric Acid Ph of Acids and Bases Potassium Bromate Weak Acid Examples Weak Bases Magnesium Hydroxide Monosodium Glutamate Potassium Hydroxide Nitrous Acid Henderson Hasselbalch Equation Difference between Alkali and B...Properties of Bases Sodium Citrate Ammonium Phosphate Chemical Indicators Chromic Acid Perchloric Acid Uses of Sodium Hydroxide Zinc Acetate

Yamini Saini

Updated on Jun 30, 2021 06:41 IST

A base is a chemical species that donates electrons, accepts protons or releases hydroxide ions(OH-) ions in aqueous solution. The classification of bases is according to their degree of dissociation in water and reactivity.

Strong base completely dissociates its ions in water - NaOH, KOH.

A weak base is an incomplete dissociation in water - NH3

Superbase is better at deprotonation than the strong base. Examples of superbases are Sodium hydride(NaH), ortho-diethynylbenzene dianion.

Table of Contents

Properties of Bases
Reaction with Metals
Reaction with Water
Illustrative Examples
FAQs on Properties of Bases

Properties of Bases

The bases have pH value in the range of 7-14.
They are bitter in taste, corrosive.
Aqueous solutions of bases conduct electricity due to the formation of ions.
The bases are slippery and soapy to touch.
Never taste or touch them as they may cause harm.

Reaction with Metals

Hydrogen gas is released when a base like NaOH reacts with Zinc metal. However, it is not possible with all metals.

2NaOH + Zn → Na2ZnO2 + H2O

Reaction with Acid

The reaction between an acid and base to give salt and water is known as neutralization reaction.

NaOH + HCl → NaCl + H2O

Reaction with Water

The bases which are soluble in water are called alkalis. They generate Hydroxide ions in water. In general, the mixing of a base with water results in the decrease of OH- ions per unit volume.

Reaction with Oxides

Bases react with acidic oxides to produce salts and water. Acidic oxides are oxides of nonmetals or metals of high oxidation states.

Reaction with an Ammonium Salt

On reaction with ammonium salts, ammonia gas is released. For example, the reaction of NaOH with ammonium chloride yields ammonia, sodium chloride and water.

Reaction with Other Salts

Bases undergo reaction with other salts to produce salts and other bases.

Here, ammonium hydroxide reacts with a solution of ammonium sulphate to yield aluminium hydroxide and ammonium sulphate.

Properties of Bases for Class 10

In this chapter, you will study the reactions of acids and bases with the other chemicals. The weightage of this topic is less than 5 marks. Questions are in the form of both objective and subjective type.

Illustrative Examples

What is the pH of 0.05M solution of KOH?

KOH is a strong base and dissociate completely into K+ and OH-

pOH = - log (0.05)

pOH = -(-1.3)

pOH = 1.3

pH = 14- pOH = 14-1.3 =12.7

Calculate the pH of 1 × 10–4 molar solution of NaOH?

NaOH(aq) ⎯→ Na+(aq) + OH–(aq)

One mole of NaOH would give one mole of OH– ions.

[OH–] = 1 × 10–4 mol L–1

pOH = –log[OH–] = –log × 10–4 = –(–4) = 4

Since pH + pOH = 14

pH = 14 – pOH = 14 – 4 = 10

What is meant by Lewis acids and Lewis bases?

Lewis acid accepts an electron pair (electrophile) and has vacant orbitals.

Lewis base donates an electron pair (nucleophile) and has lone-pair electrons.

FAQs on Properties of Bases

Q. What are the common uses of bases?

A. For manufacturing of soaps, paper, textile, detergents.

As a reagent in the laboratory.
In the preparation of medications.

Q. What are the differences between alkalis and bases?

A. All alkalis are bases, but not bases are alkalis. Bases neutralize acids. Alkalis releases OH- ions and accepts protons.

Q. What are Antacids?

A. Antacids are weak bases that neutralize the acid in the stomach. The two main types of bases used in antacids are carbonates and hydroxides.

Q. Name list of common indicators in basic solution?

A. Litmus - Blue Phenolphthalein - Pink Methyl orange - Yellow

Q. Why is Sodium hydroxide called caustic soda?

A. NaOH is corrosive towards organic matter and breaks down the skin and flesh proteins to a pasty mass. This is called caustic action, and due to this property, it is known as caustic soda.