Lowell High School Chemistry

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Stoichiometry Practice Problems:

 

 

Practice Problem #1:

Oxygen gas can be produced by decomposing potassium chlorate using the reaction below. If 138.6 g of KClO3 is heated and decomposes completely, what mass of oxygen gas is produced?

 

            KClO3 (s)  -->  KCl (s)  +  O2 (g)                  [unbalanced]

 

Answer to Practice Problem #1

 

 

Practice Problem #2:

Identify the limiting reagent for the given combination of reactants. Calculate how many grams of whatever substance will be in excess and how many grams of HF will be made.

 

            F2 (g)  +  NH3 (g)  -->  N2F4 (g)  +  HF (g)               [unbalanced]

        5.33 mol    2.22 mol

 

Answer to Practice Problem #2

 

 

Practice Problem #3:

How many grams of aluminum sulfate are produced if 23.33 g Al reacts with 74.44 g CuSO4?

 

            Al (s)  +  CuSO4 (aq) -->  Al2(SO4)3 (aq)  +  Cu (s)  [unbalanced]

 

Answer to Practice Problem #3

 

 

Practice Problem #4:

Given the following reaction, answer Parts A and B.

 

            NaClO3 (s) -->  NaCl (s) + O2 (g)                  [unbalanced]

 

Part A: 12.00 moles of NaClO3 will produce how many grams of O2?

Part B: How many grams of NaCl are produced when 80.0 grams of O2 are produced?

 

Answer to Practice Problem #4