Multiple Conversions

Example:

•  11.5 grams of H2 gas placed in a balloon at STP. Determine the volume of the volume of the balloon.

1.  11.5 grams x ( 1 mol / 2.0 grams ) = 5.75 mol

        5.75 mol x ( 22.4 L / 1 mol ) = 128.8 L = 129 L

    2.  11.5 grams x ( 1 mol / 2.0 grams ) x ( 22.4 L / 1 mol ) = 129 L



Example: 

•  A car tire contains 25.0 L of Nitrogen (N2) gas at STP. How many grams of Nitrogen is this?

•   25.0 L x (1 mol / 22.4 L) x (28 grams / 1 mol) = 31.25 grams  =  31.3 g

Example:

•  How many Formula Units are there in 3.5 grams of Nickel (ll) Oxide ?
•  Ni 2+  O 2-  
•  NiO
•  3.5 x (1mol / 74.7 grams) x (6.02 x 10²³  F.U. / 1 mol)  = 2.8 x 10²² F.U.

Example:

•  A sample of Oxygen (O2) contains 3.5 x 10²¹ molecules. How many grams of Oxygen is this ?
• 3.5 x 10²¹  molecules x (1 mol / 6.02 x 10²³ molecules) x (32 grams / 1 mol) = 0.19 grams

Example:

•  A container of Oxygen holas 35.0 L of methane (CH4) gas at STP. How many molecules of methane is this?
• 35.0 L x (1mol / 22.4 L) x (6.02 x 10²³ molecules / 1 mol) = 9.41 x 10²³ molecules

Example:

•  A sample of NO2 occupies 7.50 L. How many oxygen atoms are present in this sample?
• 7.50 L x (1 mol / 22.4 L) x (6.02 x 10²³ molecules / 1 mol) x (2 atoms / 1 molecules) = 4.03 x 10²³ atoms

Example:

•  Determine the mass of 10 molecules of Carbon Dioxide.
•  CO2
•  10 molecules x (1 mol / 6.02 x 10²³ molecules) x (44 g / 1 mol) = 7.3 x 10^-22 grams  

-Eva