# Question 819ef

Dec 19, 2017

${\text{3.2 g cm}}^{- 3}$

#### Explanation:

The density of a material is simply the mass of exactly one unit of volume of that material.

In this case, you know that a ${\text{25-cm}}^{3}$ volume of this material has a mass of $\text{81 g}$, so in order to find its density, you must use this information to figure out the mass of ${\text{1 cm}}^{3}$ of this material.

You can set up a conversion factor that has the mass of the sample as the numerator and the volume it occupies as the denominator.

You will have

1 color(red)(cancel(color(black)("cm"^3))) * "81 g"/(25color(red)(cancel(color(black)("cm"^3)))) = "3.24 g"#

So, if ${\text{1 cm}}^{3}$ of this material has a mass of $\text{3.24 g}$, you can say that the density of the material is equal to

$\textcolor{\mathrm{da} r k g r e e n}{\underline{\textcolor{b l a c k}{{\text{density"))) = "3.24 g cm"^(-3) ~~ color(darkgreen)(ul(color(black)("3.2 g cm}}^{- 3}}}}$

The answer must be rounded to two sig figs, the number of sig figs you have for your values.