Density

* Density is a measure of mass / volume
* When calculating density the following chart makes the task a lot easier to understand…


Density
* (D = m / v)
(Molar Mass) (Molar Volume)
Mass ------ Moles ------ STP

*
(Avogadro’s #)

Molecules
*
(Subscripts)
*
Atoms


* Here are some examples / solutions to density problems:


Ex. Compound “X” has a density of 3.0 g/ml. Determine the mass of 12 mL of X. How many moles are in 12 mL of X…?

Step # 1. 12 mL x 3g /1 mL = 36g


Step # 2. H2O ~ 2(1.0) + 16.0 = 18.0g


Step # 3. 36g x 1 mol / 18.0g = 2.0 mol


Ex. An unknown compound has a molar mass of 73.0 g/mol. If 0.15 mol occupies a volume of 50 mL, determine the compound’s density.

Step # 1. 0.15 mol x 73.0g / 1mol = 10.95g

Step # 2. 10.95g / 50mL = 0.219 g/mL ~ 0.22 g/mL

Cool Video :)