In a large container in an oil refinery, three oils of different densities are mixed. No chemical activity occurs.

Question 14

In a large container in an oil refinery, three oils of different densities are mixed. No chemical activity occurs.

The mixture consists of

1200 kg of oil of density 1100 kg m^-3,

1500 kg of oil of density 860 kg m^-3,

4000 kg of oil of density 910 kg m^-3.

What is the density of the mixture?

A 927 kg m^-3                    B 957 kg m^-3                    C 1010 kg m^-3                                 D 1080 kg m^-3

Reference: Past Exam Paper – June 2016 Paper 12 Q13

Solution:

Answer: A. 

Density of mixture = total mass / total volume

Density = mass / volume

Volume = mass / density

Volume of the 1200 kg oil = 1200 / 1100 = 1.091 m^-3

Volume of the 1500 kg oil = 1500 / 860 = 1.744 m^-3

Volume of the 4000 kg oil = 4000 / 910 = 4.396 m^-3

Total mass = 1200 + 1500 + 4000 = 6700 kg

Total volume = 1.091 + 1.744 + 4.396 = 7.231 m^-3

Density of mixture = 6700 / 7.231 = 926.6 = 927 kg m^-3