Five mL of ethanol has a mass of 3.9 g, and 5.0 mL of benzene has a mass of 4.4 g. Which liquid is denser?
As you know, density is defined as mass per unit of volume.
#color(blue)("density" = "mass"/"unit of volume")#
So, what you it mean for one substance to be denser than another substance?
Well, the denser substance would have to have a bigger mass in the same volume. In your case, you know that
This tells you that benzene is denser than ethanol, since you'd get a bigger mass of benzene in the same volume.
Now, you can compare the densities of the two substances by making sure that you're using the same unit of volume for both substances. In this case, volume is given to you in milliliters, which means that the unit of volume will be
So, what would the mass of
#1 color(red)(cancel(color(black)("mL"))) * "3.9 g"/(5.0color(red)(cancel(color(black)("mL")))) = "0.78 g"#
The density of ethanol,
Likewise, the mass of
#1 color(red)(cancel(color(black)("mL"))) * "4.4 g"/(5.0color(red)(cancel(color(black)("mL")))) = "8.8 g"#
The density of benzene,
#rho_b > rho_e#
you can say once again conclude that benzene is slightly denser than ethanol.