Review For Unit Test 3 (Acids and Bases)

Review Topics:

  • Dissociation of Ionic Compounds
  • Separation of Molecular Compounds
  • Ionization of Acids
  • Diagnostic Testing of Solutions (conductivity, litmus)
  • Solubility
  • Solubility Equilibrium
  • Percent By Mass Concentration
  • Parts Per Million Concentration
  • Molar Concentration
  • Concentration of Individual Ions
  • Dilution
  • Preparing Standard Solutions
  • Arrhenius Theory
  • Modified Arrhenius Theory and the Hydronium Ion
  • Strong and Weak Acids
  • Strong and Weak Bases
  • Monoprotic and Polyprotic Acids and Bases
  • pH, [H3O+(aq)], pOH, and [OH-(aq)] Calculations
  • Determining pH with Acid-Base Indicators

Remaining of Period To Work on Questions from Review Package

Chem 20Chapter 3 Review Questions

  1. Is a saturated solution always a concentrated solution? Give an example to illustrate your answer.

Not necessarily. Although saturation means that the solution cannot get concentrated anymore, it does not mean that the concentration is high, as there might be solutions that a saturated at low concentrations.

  1. Define the term “solubility”. What factors affect the solubility of solids, liquids and gases in other liquids?

Solubility describes a solutes ability to dissolve in a given solvent to form a solution.
Factors affecting solubility: TEMP and PRESSURE
INCREASE TEMP: Solids increase solubility. Liquids no change. Gases decrease solubility. E.g., Heat effect on: 1) dissolving sugar in coffee? 2) Dissolving CO2 into pop?

INCREASE PRESSURE: Gases increase solubility. Liquids and solids no change. E.g. opening pop can decreases pressure and CO2 solubility.

  1. Iron concentration of 0.2 to 0.3 ppm in water causes fabric staining when washing clothes. A typical wash uses 12.0 L of water. What is the maximum mass of iron that can be present without staining the clothes?

g

  1. What are the concentrations of each ion in the following solutions?
  2. 4.12 mol/L ammonium chloride

[NH4+] = 4.12 mol/L

[Cl-] = 4.12 mol/L

  1. 0.275 mol/L barium hydroxide

[Ba2+] = 0.275 mol/L
[OH-] = 0.550 mol/L

  1. 0.543 mol/L ammonium phosphate

[NH4+] = 1.63 mol/L
[PO43-] = 0.543 mol/L

  1. Calculate the new concentration when the following dilutions are performed:
  2. 25.0 mL of 1.50 mol/L hydrochloric acid is diluted to 150 mL of solution

C1V1=C2V2

C2 = 0.250 mol/L

  1. 1.3 L of 1.2 mol/L sodium nitrate diluted to 7.3 L of solution

C2 = 0.214 mol/L

  1. 500 mL of 3.75 mol/L ammonium phosphate, with 2.75 L of water added

C2 = 0.682 mol/L

  1. A sample of lemon juice has a pH of 2. A sample of club soda has a pH of 5. How much more concentrated is the hydronium ion in the lemon juice than in the club soda?

Each pH unit is a factor of 10.
So lemon juice is 1000 more acidic than club soda.

  1. The pH of pure water is 7.00. Explain why.

[OH-] equals [H3O+]

  1. Which of the solutions in each pair has a higher pH? Explain why.
  2. 0.10 mol/L solution of a weak acid; 0.010 mol/L solution of the same acid

More hydronium ions in A, so B has lower pH

  1. 0.10 mol/L solution of an acid; 0.10 mol/L solution of a base

Base has way less hydroniums, so higher pH

  1. a solution with a pOH of 7.0; a solution with a pOH of 8.0

pOH of 8 = pH of 6, so A has higher pH

  1. 0.10 mol/L solution of a strong acid; 0.10 mol/L solution of a weak acid

Strong acid ionizes 100%, so way more hydroniums. B will have higher pH.

  1. 0.10 mol/L solution of a strong base; 0.10 mol/L solution of a weak base

Strong bases dissociates 100%, so way more hydroxides. A will have higher pH

  1. 0.10 mol/L solution of H2SO4; 0.10 mol/L solution of HSO4-

A is strong acid. So it will have lower pH. B will have higher pH

  1. Fill in the table with the appropriate information:

Solution / [H3O+(aq)]
(mol/L) / [OH-(aq)]
(mol/L) / pH / pOH
1 / 3.11 x 10-8 / 3.22 x 10-7 / 7.507 / 6.493
2 / 2.25 x 10-4 / 4.45 x 10-11 / 3.648 / 10.352
3 / 1.20 x 10-6 / 8.33 x 10-9 / 5.92 / 8.08
4 / 0.240 / 4.17 x 10-14 / -0.620 / 14.62
  1. Which of the solutions in #9 is the most acidic? The most basic?

Solution 4 (highest hydronium concentration)

  1. A student tests 4 unknown solutions with the following observations:

Solution A: doesn’t conduct electricity, blue litmus stays blue, red litmus stays red

Solution B: does conduct electricity, blue litmus stays blue, red litmus turns blue

Solution C: does conduct electricity, blue litmus stays blue, red litmus stays red

Solution D: does conduct electricity, blue litmus turns red, red litmus stays red

Identify the type of compound that could cause each of these observations.

A = Sugar water (molecular)
B = Base
C = Salt water (ionic)
D = Acid

  1. Acid-base indicators are used to identify the possible pH of 3 unknown solutions. The following observations are made:

Indicator / Solution A / Solution B / Solution C
methyl red / red / yellow / yellow
phenol red / yellow / red / orange
phenolphthalein / colourless / pink / colourless
bromothymol blue / yellow / blue / blue
possible pH range: / pH < 4.8 / 10 < pH / 7.6-8.0