# How do you find the volume of an irregular object like a rock or sphere in chemistry?

Nov 16, 2015

Use the method of displacement of water.

#### Explanation:

Fill a measuring cylinder to a known volume of water, say ${V}_{0}$.

Place the solid object of unknown volume ${V}_{s}$ in the water and ensure it is totally submerged.

Read off the new volume ${V}_{1}$.

The volume of the displaced water is then equal to the volume of the object in the water, ie ${V}_{s} = {V}_{1} - {V}_{0}$.

This method was initially discovered by Archimedes who was challenged to find a method to prove whether the king's crown was made of pure gold or not. He decided to try and find the density of the crown and compare it to data sheets for the density value of gold. However, since $\rho = \frac{m}{V}$, he battled to find the volume of the irregular shaped crown and came to the discovery of the method described above when he climbed into his bath one day filled to the brim and water overflowed from the sides. He was apparently so overjoyed that he ran down the street naked celebrating.