Question #d3948

1 Answer
Jun 15, 2017

Answer:

#"0.002 g mL"^(-1)#

Explanation:

The density of a substance, #rho#, tells you the mass of exactly one unit of volume of said substance.

In your case, the sample of carbon dioxide has a mass of #"100 mL"#, so you can say that one unit of volume will be #"1 mL"#. This means that your goal here is to figure out the mass of #"1 mL"# of carbon dioxide.

Now, you know that the mass of #"100 mL"# of carbon dioxide is equal to #"0.196 g"#.

You can find the density of carbon dioxide by dividing the mass of the sample by the total volume it occupies

#rho = "0.196 g"/"100 mL"#

since this will get you the mass of #"1 mL"# of carbon dioxide

#rho = "0.196 g"/(100 * "1 mL") = "0.196 g"/100 * 1/"1 mL"#

# = "0.00196 g" * 1/"1 mL" = "0.00196 g"/"1 mL"#

# = color(darkgreen)(ul(color(black)("0.002 g mL"^(-1))))#

The answer must be rounded to one significant figure, the number of sig figs you have for the volume of the sample.

You can thus say that #"1 mL"# of carbon dioxide has a mass of #"0.002 g"#.

SIDE NOTE We usually express the density of a gas in grams per liter, #"g L"^(-1)#.

In your case, the density of carbon dioxide in grams per liter is equal to

#0.002 color(white)(.)"g"/(1color(red)(cancel(color(black)("mL")))) * (10^3color(white)(.)color(red)(cancel(color(black)("mL"))))/"1 L" = "2 g L"^(-1)#

This is very close to the density of carbon dioxide at STP conditions

https://en.wikipedia.org/wiki/Carbon_dioxide