Question

One milliliter of an unknown liquid contains about 20 drops. One gram of this liquid contains 3.34 x 10^22 molecules. How many molecules are in one drop of the unknown liquid?(density = 1.212g/mL)

Answer 1

Density of the liquid = 1.212 g/mL
this means, mass of 1 ml of liquid is 1.212 g
1 ml has 20 drops
Hence mass of 20 drops = 1.212 g
therefore mass of 1 drop = 1.212 g / 20 = 0.0606 g
1 gram has 3.34 x 10²² molecules.
Hence molecules in 0.0606 g = (3.34 x 10²² / 1 g) x 0.0606 g
= 2024.04 x 10¹⁸