Stoichiometry : Sample Problems

1. A sample contains 27.1 g of calcium oxide.  How many moles of calcium oxide are in the sample?

NOTE: Use the Periodic Table to find the molecular mass (grams per mole)
 
 

2. How many atoms are in 0.652 mol of iron?

NOTE: A mole is by definition 6.0220 x 10²³ particles which can generally be rounded to 6.02 x 10²³.

 

 

3. How many liters does 3.8 moles of O₂ occupy at STP (standard temperature and pressure)?

NOTE: At STP, 1 mole of any gas = 22.4L.  STP is 273K (0C) and 1 atm.

 

 

4. A solution of NaCl has a molarity of 0.549 M.  How many moles are in 350. mL of this solution?

NOTE: Molarity is MOLES per LITER.  The volume in milliliters must be converted to Liters.

 

 

 
6. How many grams of carbon dioxide are there in a container with a volume of 4.50L at STP?
 

 
7. How many moles of nitrogen are there in a 7.45 mol sample of ammonium phosphate?
 

 
8.  If 120. g of propane, C₃H₈, is burned in excess oxygen, how many grams of water are formed?
 

 
9. 90.0 g of FeCl₃ reacts with 52.0 g of H₂S.  What is the limiting reactant?  What is the mass of HCl produced?  What mass of excess reactant remains after the reaction?
NOTE: The limiting reactant is the reactant that limits the amount of product that can be formed and is completely consumed during the reaction.