Aqueous Solutions and Acid-Base Stoichiometry WS
1. Write the balanced molecular equation and the balanced net ionic equation the reactions that
occur when the following are mixed. Unless otherwise indicated, all reactants are aqueous.
a)
b)
c)
d)
Potassium hydroxide and nitric acid
Barium hydroxide and hydrochloric acid
Solid silver hydroxide and hydrobromic acid
Strontium hydroxide and hydroiodic acid
2.
Write the balanced molecular equation and the balanced net ionic equation for the reactions
that occur when the following are mixed.
a) Hydrochloric acid and sodium sulfite
b) Ammonium chloride and strontium hydroxide
c) Potassium carbonate and hydrochloric acid
3.
What volume of each of the following acids will react completely with 50.00 mL of 0.200 M
NaOH?
a) 0.150 M nitric acid
b) 0.200 M acetic acid (one acidic hydrogen)
4.
What volume of each of the following bases will react completely with 25.00 mL of 0.200 M
hydrochloric acid?
a) 0.0500 M strontium hydroxide
b) 0.250 M potassium hydroxide
5.
75.0 mL of 0.250 M of hydrochloric acid is added to 225.0 mL of 0.0500 M barium hydroxide
solution. What is the concentration of the excess H+ or OH- ions left in this solution?
6.
A 25.00 mL sample of hydrochloric acid solution requires 24.16 mL of 0.106 M sodium
hydroxide for complete neutralization. What is the concentration of the original hydrochloric
acid solution?
7. A 10.00 mL sample of vinegar, an aqueous solution of acetic acid, is titrated with 0.5062 M
sodium hydroxide, and 16.58 mL is required to reach the equivalence point.
a) What is the molarity of the acetic acid?
b) If the density of the vinegar is 1.006 g/cm3, what is the mass percent of acetic acid in the
vinegar?
8. A student titrates an unknown amount of potassium hydroxide phthalate (KHP) with 20.46 mL of
a 0.1000 M sodium hydroxide solution. The molar mass of KHP is 204.22 g/mol. What mass of
KHP was titrated by the sodium hydroxide?
9. The concentration of a sodium hydroxide solution was determined by using it to titrate a
solution of KHP. The molar mass of KHP is 204.22 g/mol. In the titration, 34.67 mL of the
sodium hydroxide was required to react with 0.1082 g KHP. Calculate the molarity of the
sodium hydroxide.
AP Problem #1
The molecular weight of a monoprotic acid HX was to be determined. A sample of 15.126 grams of HX
was dissolved in distilled water and the volume brought to exactly 250.00 mL in a volumetric flask. Several
50.00 mL portions of this solution were titrated against NaOH solution, requiring an average of 38.21 mL
of NaOH.
The NaOH solution was standardized against oxalic acid dihydrate, H2C2O4.2H2O (molecular weight:
126.066 g/mol). The volume of NaOH solution required to neutralize 1.2596 g of oxalic acid dihydrate was
41.24 mL.
(a)
(b)
(c)
(d)
Calculate the molarity of the NaOH solution.
Calculate the number of moles of HX in a 50.00 millilitre portion used for titration.
Calculate the molecular weight of HX.
Discuss the effect of the calculated molecular weight of HX if the sample of oxalic acid dihydrate
contained a nonacidic impurity.
AP Problem #2
The percentage by weight of nitric acid, HNO3, in a sample of concentrated nitric acid is to be determined.
(a) Initially a NaOH solution was standardized by titration with a sample of potassium hydrogen
phthalate, KHC8H4O4, a monoprotic acid often used as a primary standard. A sample of pure
KHC8H4O4 weighing 1.518 grams was dissolved in water and titrated with the NaOH solution. To
reach the equivalence point, 26.90 mL of base was required. Calculate the molarity of the NaOH
solution. (Molecular weight: KHC8H4O4 = 204.2 g/mol)
(b) A 10.00 mL sample of the concentrated nitric acid was diluted with water to a total volume of
500.00 mL. Then 25.00 mL of the diluted acid solution was titrated with the standardized NaOH
solution prepared in part (a). The equivalence point was reached after 28.35 mL of the base had
been added. Calculate the molarity of the concentrated nitric acid.
(c) The density of the concentrated nitric acid used in this experiment was determined to be 1.42
g/mL. Determine the percentage by weight of HNO3 in the original sample of concentrated nitric
acid.