1. THE MOLE Chapter 10: Chemical Quantities

2. 10.1 Measuring Matter What is a mole? It is the SI unit that measures the amount of substance.

3. Mole Mass s Volume Number of Particles

4.  Avogadro’s number  Simply multiply by 6.02 x 10 23

5.  How many moles of magnesium is 1.25 x 10 23 atoms of magnesium?  How many atoms are in 2.12 mol of propane? (C 3 H 8 )

6.  Multiply by the molecular mass of the substance.  Molar mass: mass (in grams) of one mole of the substance

7.  How many grams are in 9.45 mol of dinitrogen trioxide (N 2 O 3 )?  How many moles in 92.2 g of iron (III) oxide (Fe 2 O 3 )?

8.  The Special Number 22.4

9.  volume varies with changes in temperature and pressure › usually measured at STP (0 o C; 101.3 kPa) › at STP, one mole of any gas occupies a volume of 22.4 L

10.  Determine the volume, in liters, of 0.60 mol SO 2 gas at STP.  The density of a gaseous compound containing carbon and oxygen is 1.964 g/L at STP. Determine the molar mass of the compound.

11.  Mass / molecular mass  Volume / 22.4  Number of particles / Avogadro’s number

12.  Percent by mass of each element in a compound  % mass of element = Grams of element X Grams of compound X 100

13.  9.03 g Mg combine completely with 3.48 g N to form a compound. What is the % composition of this compound?  Calculate the % composition of ethane (C 2 H 6 ).

14.  Calculate the mass of hydrogen in 350 g C 3 H 8.

15.  Lowest whole number ratio of atoms of an element in a compound. › May or may not be the same as the molecular formula!

16.  Give the empirical formula for a compound which is 25.9% Nitrogen and 74.1% Oxygen.  Assume it is a 100g sample, so 25.9g N and 74.1g of O  25.9/14 =1.85 moles of N 74.1/16 = 4.63 moles of O 1.85/1.85 = 14.63/1.85 = 2.5 Double both numbers to get a whole number ratio… N 2 O 5

17.  Calculate the empirical formula of a compound that is 79.8% C and 20.2% H.  Calculate the molecular formula of a compound whose molecular mass is 62 g/mol and empirical formula is CH 3 O.

18.  Compounds with specific numbers of water molecules bound to their atoms are called hydrates.  In the formula, a dot is used to show that water is bonded. Use a prefix to name the hydrate. › Na 2 CO 3 ∙ 10H 2 O Sodium carbonate decahydrate

19.  In order to analyze a hydrate, you must first find the number of moles of water associated with one mole of the hydrate. › Heat the sample to drive off the water, then you can mass the anhydrous compound and determine the moles of water.

20.  An 11.75g sample of a common hydrate of cobalt (II) chloride is heated. After heating, 0.0712 mol of anhydrous cobalt chloride remains. What is the formula and the name of this hydrate?

21. THE END