CHEMISTRY SHENANIGANS

Today in class, we reviewed the past topics of conversions to and from Moles, Volume, Molar Mass, Density, and Atoms and Molecules. Don't forget about Mr. Doktor's chart!

Density <----> Molar Mass <----> Mole <-- (conversion factor is 6.02 x 10²³)--> Atoms and Molecules (the subscripts)
                                                  
Mole <--(conversion factor is 22.4 L/mol or vice versa)--> Volume                                                   

Below, we have some examples..

Ex. (in class) 1.25 L of an unknown gas has a mass of 3.47 g. What is the molar mass if it is 22.4 L/mol?

1.25 L x 1 mol  =  0.0558 mol
              22.4 L

Molar Mass  =    3.47 g       =  62.2 g/mol
                       0.0558 mol

Ex. (in class) 250 mL of a gas which is known to contain one sulphur atom and an unknown number of fluorides has a mass of 1.63 g at STP. Find the molar mass, then the number of fluoride atoms. (SFx)

a) the Molar Mass
0.25 L x   1 mol   =  0.011 mol
                22.4L

1.63g / 0.011 mol = 146.048 g/mol

b) the number of fluoride atoms
1(32.1) + x(19) = 146
                  19x = 146-32.1
                      x = 6
Ex.Calculate the volume of 11.2 mol of HCN (g) at STP.
11.2 mol x 22.4 L  =  250.88 L = 251 L
                   1 mol

Ex. What is the volume of 1.3 g of NO₂ at STP?
1N + 2O --> 1 (14) + 2(16) = 46 g/mol
1.3 g  x  1 mol   x   22.4 L  = 0.633 L
                46 g       1 mol


Here are two videos to help you review!