Question

Question #03bbc

Answer 1

`"8.64 g"`

Explanation:

A substance's density tells you the mass of exactly `1` unit of volume of said substance.

In your case, the density of sodium chloride is said to be equal to `"2.16 g cm"^(-3)`. This tells you that every `"1 cm"^3` of sodium chloride has a mass of `"2.16 g"`.

You can write this as a ratio of mass to volume

`"2.16 g"/"1 cm"^3->` the density of sodium chloride

Now, you know that your sample has a volume of `"4.00 cm"^3`. Your goal here is to figure out what mass corresponds to `"4.00 cm"^3` knowing that `"2.16 g"` correspond to `"1 cm"^3`.

To do that, set up the equation as

`(color(blue)(?)color(white)(.)"g")/"4.00 cm"^3 = "2.16 g"/"1 cm"^3`

Rearrange and solve to find

`color(blue)(?) = (4.00 color(red)(cancel(color(black)("cm"^3))))/(1color(red)(cancel(color(black)("cm"^3)))) * "2.16 g" = color(darkgreen)(ul(color(black)("8.64 g")))`

The answer is rounded to three sig figs.