Density conversion:

http://www.youtube.com/watch?v=fqLCwuKMBMA

1. question: Water has a density of 1.0g/ml. Determine the mass of 11.5ml of water

                     How many moles are in 11.5 ml of water?

    answer: 10g/ml x 11.5ml=11.5g=12g

                  11.5g x 1mol/ 18.0g=0.64 mol

2. question: An unknown compound has a molar mass of 65.0g/ mol. If 0.25mol occupies 

                    a volume of 50ml determine the compound's density

    answer: 0.25mol x 65.0g/ mol= 16.25g 

                  16.25/50ml= 0.325g/ml= 0.33g/ml

3. question: The density of aluminum is 2.70g/ml. A solid piece of aluminum has a volume

                     of 45.0ml. Determine the number of aluminum atoms present

    answer: 2.70g/ml x 45.0ml x 1mol/27.0g x 6.02 x 10^23 atoms/ 1 mol

                  = 2.71 x 10^24 atoms

4 question: Copper has a density of 8.96g/ ml. Determine the numbers of atoms in a copper

                   key that has a volume of 20ml TRY THIS YOURSELF!! :D

Density of gases:

1. The density of gases varies with temperature 

2. An STP we can find density by: 

    MM [molar mass]/ 22.4 l/mol [molar volume]

1. question: Calculate the density of 0,2 at STP

     

    answer: 32.0g/mol / 22.4l/mol=1.43g/L 

2. question: Determine the density of methane[ CH,4] at STP

    answer: 16.0g/mol / 22.4L/mol=0.714g/L