Question

Question #8b75f

Answer 1

The density of a substance is the amount of mass per unit volume. The density equation is:

density = mass/volume

Your unknown (x) is mass. To solve the density equation for mass, you need to multiply both sides of the equation by volume:

(volume) x density = mass/volume (volume)

This cancels volume on the right side, leaving only mass.
So density x volume = mass or we can rewrite it as:
mass = density x volume

The volume in your problem has a numerical value of 65.417 but no volume units are included, which is a problem. Volume can be `mL, cm^3, m^3`, etc. The unit for the answer 11.34 is in grams, so mass is in grams. When grams are used in a density value, the volume is usually `cm^3` or `mL`. So I'm going to use `g`/`cm^3` as the density unit. So 11.34g should be be 11.34`g`/`cm^3`. To find the mass, do the following:

Unknown:
mass = ?g

Known:
volume = 65.417`cm^3`
density = 11.34`g`/`cm^3`

Equation:
density = mass/volume

Solution:
mass = density x volume = 11.34`g`/`cm^3` x 65.417`cm^3` = 741.8g
The volume unit `cm^3` cancels, leaving grams (g).

Check Answer:
density = mass/volume = 741.8`g`/65.417`cm^3` = 11.34`g`/`cm^3`

In science classes, numbers rarely occur without some kind of unit. Those units are part of the number and should not be left off and should be treated the same as the number when used in calculations.

There is a neat little device called the density triangle that can be used to help you determine whether to divide or multiply to find an answer to a density problem.

M means mass, D means density, and V means volume. You cover the variable that you don't know, and the locations of the other two variables indicates how you should solve your problem.

If you want to find mass, cover the M, and the D and V are next to each other. This means that you should multiply density and volume to find mass. `M = D` x `V`

If you want to find density, cover the D, and the M is over the V, which means that you should divide the mass by the volume to find density. `D = M/V`

If you want to find volume, cover the V, and the M is over the D, which means you should divide the mass by the density.
`V = M/D`