Worksheet – Stoichiometry II
1. Chlorine is used by textile manufacturers to bleach cloth. Excess chlorine is
destroyed by its reaction with sodium thiosulfate, Na2S2O3:
Na2S2O3(aq) + 4Cl2(g) + 5H2O(l)  2NaHSO4(aq) + 8HCl(aq)
a. Is the chemical equation balanced?
b. What are the mole ratios between all substances?
c. How many moles of Na2S2O3 are needed to react with 0.12 mol. of
Cl2?
d. How many moles of HCl can form from 0.12 mol. of Cl2?
e. How many moles of H2O are required for the reaction of 0.12 mol. of
Cl2?
f. How many moles of H2O react if 0.24 mol. of HCl is formed?
2. Using the following equation:
2NaOH + H2SO4  2H2O + Na2SO4
a. Is the chemical equation balanced?
b. What are the mole ratios between all the substances?
c. How many moles of water will be produced when 0.578 mol. of sulfuric
acid (H2SO4) is consumed?
d. How many grams of sodium sulfate will be formed if you start with 200
grams of sodium hydroxide and you have an excess of sulfuric acid?
3. Using the following equation:
Pb(SO4)2 + 4LiNO3  Pb(NO3)4 + 2Li2SO4
a. Is the chemical equation balanced?
b. What are the mole ratios between all the substances?
c. How many moles of lead(II) sulfate is needed to produce 2.35 mol. of
lithium sulfate?
d. How many grams of lithium nitrate will be needed to make 250 grams
of lithium sulfate, assuming that you have an adequate amount of lead
(IV) sulfate to do the reaction?
4. Oxygen gas can be produced by decomposing potassium chlorate using the
reaction below:
KClO3(s)  KCl(s) + O2(g)
If 138.6 g of KClO3 is heated and decomposes completely, what mass of
oxygen gas is produced?
5. In dilute nitric acid, HNO3, copper metal dissolves according to the following
equation:
3Cu(s) + 8HNO3(aq)  3Cu(NO3)2(aq) + 2NO(g) + 4H2O(aq)
How many grams of HNO3 are needed to dissolve 11.45 g of Cu?