Question

The density of graphite is:
A.$3.52{\text{ g c}}{{\text{m}}^{ - 3}}$
B.$2.3{\text{ g c}}{{\text{m}}^{ - 3}}$
C.${\text{1}}{\text{.2 g c}}{{\text{m}}^{ - 3}}$
D.$4.2{\text{ g c}}{{\text{m}}^{ - 3}}$

Answer 1

To solve this, it is required to have knowledge about graphite and its properties. Graphite is one of the allotropes of carbon, the other being diamond. The carbons in graphite are arranged in a hexagonal structure. To determine the density of graphite, we use the term apparent density. This is because the structure of graphite is porous and has a lot of free space between it. So, normal density would give us an incorrect value.

Complete step by step answer:
As we know that, density is calculated as mass per unit volume. But that is true only if the molecules do not have voids or flaws. In case of graphite, as it has a lot of voids and is porous, we use a new term called apparent density. The density can be calculated in two methods. The simple method includes measurement of volume of the graphite crystal using its dimension. Then the weight of the crystal is divided by this volume. The other method is by water density. In this method, the weight of graphite is taken in the air and then it is submerged in water. The graphite is submerged such that its weight can be measured. The weight of the water displaced is also measured. The density is then calculated using the formula: ${\text{D = }}\dfrac{{{{\text{W}}_{\text{w}}}}}{{{{\text{W}}_{\text{1}}}{\text{ - }}{{\text{W}}_{\text{2}}}}}{\text{ X}}{{\text{D}}_{\text{w}}}$ where ${{\text{W}}_{\text{w}}}$ is the weight of water displaced, ${{\text{W}}_1}$ is the weight of graphite in air, ${{\text{W}}_{\text{2}}}$ is the weight of graphite in water and ${{\text{D}}_{\text{w}}}$ is the density of water.
The density of graphite is found out experimentally to be approximately $2.3{\text{ g c}}{{\text{m}}^{ - 3}}$ .
$\therefore$ The correct option is option B, i.e. $2.3{\text{ g c}}{{\text{m}}^{ - 3}}$ .

Additional Note: Graphite is one of the allotropes of carbon, the other being diamond. The carbons in graphite are arranged in a hexagonal structure. Each carbon is bonded with three other carbon atoms which leave one free electron. This is the reason why graphite is a good conductor of electricity.

Note: Though graphite is a porous compound, it does not absorb water when it is dipped in it. The density of graphite cannot be calculated theoretically, i.e. using its crystal structure and atomic mass of carbon only.