Question

Question #819ef

Answer 1

`"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 `"25-cm"^3` volume of this material has a mass of `"81 g"`, so in order to find its density, you must use this information to figure out the mass of `"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 `"1 cm"^3` of this material has a mass of `"3.24 g"`, you can say that the density of the material is equal to

`color(darkgreen)(ul(color(black)("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.