Density and Moles!

Density and Moles today! Hurray! Density is a measure of mass per volume and is measured in g/L or g/mL.

We use the formula d=m/V to determine density.

 


EXAMPLES:
-Water has a density of 1.0 g/mL. Determine the mass of 11.5 mL of water.


-An unknown compound has a molar mass of 65.0 g/mol. If 0.25 mol occupies a volume of 50 mL determine the compound's density.


-The density of Aluminum is 2.70g/mL. A solid piece of Aluminum has a volume of 45.0 mL. Determine the number of Aluminum atoms present.


DENSITY OF GASES (@STP)
The density of gases varies with temperature. At STP we can find density by:


EXAMPLES
-Calculate the density of O₂ at STP.
-An unknown diatomic gas has a density of 1.69 g/L at STP. Determine the molar mass and chemical formula.
Next time: Percent Composition!