Question

How do you calculate equivalent units?

How do I determine the equivalent units for Magnesium and also bromobenzene specifically?

Answer 1

Ans:

• Concept of mole & equivalents

Mole	Equivalent
A number	A number
	where, n = valency, acidity, basicity, total charge on cation/anion, total gain/loss of electrons per molecule

Equivalent mass:

• It is not the property of an isolated element/compound, but is the property attained in a chemical reaction

• Definition: It is the mass of the element/molecule/compound which displaces/reacts with/releases/supply

1. 1.008 g of ‘H’
2. 8 g of ‘O’
3. 35.45 g of ‘Cl’
4. 1 mole of electrons
5. 11.2 L of H₂ gas at STP
6. 11.2 L of H₂/Cl₂ gas at STP
7. 5.6 L of O₂ gas at STP

• Finding out equivalent masses

	Equivalent mass of
1.	An element in a compound	Atomic mass/valency
2.	An acid	Molar mass/Basicity
3.	A base	Molar mass/Acidity
4.	Salt	Molar mass/Total charge on cation/anion
5.	Oxidizing / Reducing agent	Molar mass/Total gain/loss of e per molecule

Ans:

For Magnesium

Since ‘Mg’ usually becomes ‘Mg²⁺’ in almost all reactions, we can write

Equivalents of Mg = 2 x Mole of Mg

For bromobenzene

Unless the reaction is specified, it is not possible to calculate the equivalents for bromobenzene.

Ex: