Question

1000cm3 vessel is filled with 2 liquids l1 l2 of relative density of 0.75 and 1.85 respectively. If the relative density of the mixture was found to be 1.5 what volume each liquid enters the mixture

Answer 1

We have two masses in the vessel. Assume one takes x mL and the other V-x. Then the mass of the mixture in the vessel would be

$$M=xρ _ 1 ​ +(V−x)ρ _ 2$$

We know the density of the mixture:

$$\rho=\frac{M}{V}=\frac{xρ _ 1 ​ +(V−x)ρ _ 2}{V}$$

$$x=V\frac{\rho_2-\rho}{\rho_2-\rho_1}\\x=1000\frac{1.85-1.5}{1.85-0.75}=318\ cm^3\\$$

Thus, we have 318 mL of liquid 1 and 682 mL of liquid 2.