Basic Chemistry: Mole, Lon՚s and Salts, Acidity and Basicity and Arrhenius Theory

Get unlimited access to the best preparation resource for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Table of Contents

  • Introduction
  • Atoms and Elements
  • Atomic number and atomic mass
  • Periodic Table and Chemical Bonds
  • Isotopes
  • Radioisotopes
  • Periodic Table and Chemical Bonds
  • Electronegativity
  • Chemical Bond
  • Compound, substance, Molecule
  • Acidity and Basicity
  • Redox Reaction

Learning Outcomes

After studying this lesson, you shall be able to:

  • mole
  • Ions and salts
  • Arrhenius theory

Mole (Unit)

  • Mole is a chemical mass unit, defined to be molecules, atoms, or some other unit.
  • The mass of a mole is the gram formula mass of a substance.
  • The number of entities per mole is known as the Avogadro constant, and is determined empirically.
  • The currently accepted value is
  • The amount of substance of a solute per volume of solution is known as molarity used to express the concentration of a solution in the chemical laboratory.
  • The most commonly used units for molarity are mol/L (the official SI units are mol/m3) .

Ions and Salts

  • An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons. Positively charged cations (e. g. sodium cation Na + ) and
  • negatively charged anions (e. g. chloride Cl-) can form a crystalline lattice of neutral salts (e. g. sodium chloride NaCl) .
  • Examples of polyatomic ions that do not split up during acid-base reactions are hydroxide (OH-) and phosphate (PO43-) .
  • Ions in the gaseous phase are often known as plasma.
Gaseous Phase

Acidity and Basicity

Acid-Base Reaction

  • A substance can often be classified as an acid or a base.
  • There are several different theories which explain acid-base behaviour.
  • The simplest is Arrhenius theory, which states that an acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water.
Acidity and Basicity

Arrhenius Theory

According to Bronsted-Lowry acid-base theory, acids are substances that donate a positive hydrogen ion to another substance in a chemical reaction; by extension, a base is the substance which receives that hydrogen ion.

Arrhenius Theory


1. What is SI unit of Molarity:

  1. Mol/m-1
  2. mol/m3
  3. Mol
  4. None of the above

Answer: mol/m3

2. Which among the following can act as both acid and base:

  1. ~#b# ~S ~#/b# ~ ~#b# ~O ~#/b# ~2
  2. ~#b# ~H ~#/b# ~2 ~#b# ~S ~#/b# ~ ~#b# ~O ~#/b# ~4
  3. SO42-
  4. ~#b# ~H ~#/b# ~2 ~#b# ~O ~#/b# ~

Answer: ~#b# ~H ~#/b# ~2 ~#b# ~O ~#/b# ~


#Ions and salts

#Arrhenius theory