Question #03bbc

1 Answer
Stefan V.
Jun 9, 2017

#"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.

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