What is the density of a substance that has a mass of 112 g and a volume of 53 mL?

2 Answers
Jun 10, 2017

Answer:

#"Density"#, #rho~=2*g*mL^-1#

Explanation:

By definition, #rho="Mass of substance"/"Volume of substance"#.

Here, we are given the mass and the volume with respective units of #"grams"# and #"millilitres"#, and we can thus directly assess the quotient without pfaffing about with units.........

#rho_"substance"=(112*g)/(53*mL)=??*g*mL^-1#.

Would this substance float? Why or why not?

Jun 10, 2017

Answer:

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

Explanation:

Density is simply a measure of the mass of exactly one unit of volume of a given substance.

In this case, your sample is said to occupy a volume of #"53 mL"#, which means that one unit of volume is #"1 mL"#. This implies that in order to find the density of the unknown substance, you must figure out the mass of #"1 mL"#.

You already know that #"53 mL"# have a mass of #"112 g"#, so set up the equation like this

#overbrace((color(blue)(?)color(white)(.)"g")/"1 mL")^(color(red)("the density of the substance")) = overbrace("112 g"/"53 mL")^(color(red)("its known composition"))#

Rearrange and solve to find

#color(blue)(?) = (1 color(red)(cancel(color(black)("mL"))))/(53color(red)(cancel(color(black)("mL")))) * "112 g"#

#color(blue)(?) ="2.1 g"#

So, if #"1 mL"# of this substance has a mass of #"2.1 g"#, you can say that its density is equal to

#color(darkgreen)(ul(color(black)("density = 2.1 g mL"^(-1))))#

The answer is rounded to two sig figs, the number of sig figs you have for the volume of the sample.