Density question (maths)

Question

"Liquid A has a density of 0.7g/cm^3.

Liquid B has a density of 1.6g/cm^3.

 

140 g of liquid A and 128g of liquid B are mixed to make liquid C.

 

What is the density of liquid C?"

 

I would like to know how could I work out this question.

 

Thank you.

Answer 1

The simplest way to do this is to figure out the mass and volume of liquid C and then calculate the density.

 

The volume of liquid C is going to be the volumes of A and B added together.  We have the densities and masses of liquids A and B, so we can calculate their volumes.

 

Density = Mass / Volume

 

Rewrite the equation to solve for Volume:

 

Density * Volume = Mass

 

Volume = Mass / Density

 

Liquid A: 140 g / 0.7 g/cm³ = 200 cm³

 

Liquid B: 128 g / 1.6 g/cm³ = 80 cm³

 

Now that we have the volumes of A and B, we know that the volume of Liquid C is 200 cm³ + 80 cm³ = 280 cm³

 

The mass of Liquid C is 140 g + 128 g = 268 g

 

Liquid C Density = Mass / Volume = 268 g / 280 cm³ = 0.957 g/cm³