Question

Regarding graphite the following informations are available :

The density of graphite = 2.25 gm / cm3. What is C–C bond distance in graphite ?

• A. 1.68 Å
• B. 1.545 Å
• C. 2.852 Å
• D. 1.426 Å

Answer 1

Answer: (D)

1.426 Å

Answer 2

Let C – C bond distance in graphite is d A⁰

\ Surface area = 6 × $\frac{\sqrt{3}}{4}$× d²

= 6 × $\frac{\sqrt{3}}{4}$ × d² × 10^–16 cm²

\ vol. of the unit cell

= 6 × $\frac{\sqrt{3}}{4}$× d² × 10^–16 × 3.35 × 10^–8 cm³

\ mass of the unit cell

= 6 × $\frac{\sqrt{3}}{4}$× 3.35 × d² × 2.25 × 10^–24 gm.

\ 6 × $\frac{\sqrt{3}}{4}$× 3.35 × 2.25 × 10^–24 × d²

= 12 ×$\frac{10}{6}$×10^–24 × 2

\ d² = $\frac{10}{3}$ × 4 $\frac{1 \times 2}{\sqrt{3} \times 3.35 \times 2.25}$= 2.04265

or d = 1.429 Aº