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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
111
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 11
50.0 grams of H 2 SO 4 reacts completely with 40.8 grams of NaOH.
Practice Problems
8. Balance each equation and solve the problem.
a. If 40.0 g of magnesium reacts with excess hydrochloric acid
(HCl), how many grams of magnesium chloride (MgCl 2 ) are
produced?
Mg(s) ϩ HCl(aq) 0 MgCl 2 (aq) ϩ H 2 (g)
b. Determine the mass of copper needed to react completely
with a solution containing 12.0 g of silver nitrate (AgNO 3 ).
Cu(s) ϩ AgNO 3 (aq) 0 Cu(NO 3 ) 2 (aq) ϩAg(s)
c. How many grams of hydrogen chloride (HCl) are produced
when 15.0 g of sodium chloride (NaCl) reacts with excess
sulfuric acid (H 2 SO 4 )?
NaCl(aq) ϩ H 2 SO 4 (aq) 0 Na 2 SO 4 ϩ HCl(g)
d. Calculate the mass of silver phosphate (Ag 3 PO 4 ) produced if
30.0 g of silver acetate (AgCH 3 COO) reacts with excess
sodium phosphate (Na 3 PO 4 ).
AgCH 3 COO(aq) ϩ Na 3 PO 4 (aq) 0
Ag 3 PO 4 (s) ϩNaCH 3 COO(aq)
Steps in stoichiometric calculations Follow these basic steps
when performing stoichiometric calculations.
1. Write the balanced equation.
2. Determine the moles of the given substance using
a mass-to-mole conversion. Use the inverse of the
molar mass as the conversion factor.
3. Determine the moles of the unknown substance
from the moles of the given substance. Use the
mole ratio from the balanced equation as the conversion factor.
4. From the moles of the unknown substance, determine the mass of the unknown substance using a
mole-to-mass conversion. Use the molar mass as
the conversion factor.
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