Chapter 8 Review Questions - CHM 104

Ch. Ex. 120 - Oxidation and Reduction - identify oxidizing and reducing agents and species oxidized and reduced (Pool 2 of 2 In the following reaction, identify the oxidized species, reduced species, oxidizing agent, and reducing agent. Zn(s) + Ni2+(aq) → Zn2+(aq) + Ni(s) (a) Zn is the ____ and the ____ (b) Ni^2+ is the _____ and the _____

(a) oxidized species ; reducing agent (b) reduced species ; oxidizing agent

Example 4 - pH - calculate from molar concentration of strong acid (whole numbers) (Pool 1 of 3) Calculate the pH of a 1.0 × 10−3 M solution of HCl. pH =

3

Example 11 - Buffer pH - calculate using Ka and concentrations of components (Pool 3 of 7) Calculate the pH of a buffer solution in which the acetic acid concentration is 8.4 × 10−1 M and the sodium acetate concentration is 1.0 × 10−1 M. The equilibrium constant, Ka, for acetic acid is 1.8 × 10−5 pH =

3.82

Sec. Ex. 4 - pH - calculate from molar concentration of strong acid (whole numbers) (Pool 2 of 3) Calculate the pH of a 1.0 × 10^−5 M solution of HNO3. pH =

5

Sec. Ex. 11 - Buffer pH - calculate using Ka and concentrations of components (Pool 4 of 7) A buffer solution is prepared in such a way that the concentration of propanoic acid is 1.01 × 100 M and the concentration of sodium propanoate is 1.74 × 100 M. If the buffer equilibrium is described by C2H5COOH(aq) + H2O(l) ⇌ H3O+(aq) + C2H5COO−(aq with Ka = 1.34 × 10−5, calculate the pH of the solution. pH =

5.11

Ch. Ex. 36a - Acid-base reaction - write neutralization equation using the chemical formulas of reactants (Pool 1 of 4) Write an equation for the reaction of HNO3 with water. ____(aq)+____(l)→____(aq)+____(aq)

HNO3(aq)+H2O→H3O^+(aq)+NO3^-(aq)

Ch. Ex. 36b - Acid-base reaction - write neutralization equation using the chemical formulas of reactants (Pool 2 of 4) Write an equation for the reaction of HSO3− with water.

HSO3^-(aq)+H2O(l) H3O^+(aq)+SO3^2-(aq)

Sec. Ex. 10a - Titration - use molarity and volume (mL) values to calculate molarity need to neutralize given volume (Pool 2 of 5) Calculate the molar concentration of a sodium hydroxide solution if 40.98 mL of this solution were required to neutralize 11.93 mL of a 0.2000 M solution of hydrochloric acid. ____ M NaOH

0.05822

Example 10 - Titration - use molarity and volume (mL) values to calculate molarity need to neutralize given volume (Pool 1 of 5) A 23.59−mL sample of HCl of unknown concentration was transferred to a flask, a few drops of the indicator phenolphthalein were added, and the resulting solution was titrated with 0.1000 M sodium hydroxide solution. After 32.05 mL of sodium hydroxide solution were added, the indicator turned pink, signaling the chemist that the unknown and titrant had reached their equivalence point. Calculate the M of the acid. ____ M

0.1359

Ch. Ex. 1 - Calculate the moles, molarity, and pH of a KOH solution then write the net ionic equation for the neutralizati A 2.95 L solution contains 3.10 g of KOH Part 1: How many moles of KOH are present in the solution? ____ mol KOH Part 2: What is the molarity of KOH in this solution? ____ M KOH Part 3: What is the molarity of OH− in the solution? ____ M OH- Part 4 Calculate the molarity of H3O+ in the solution. ____ x 10 ^ ____ M H3O+ Part 5: Calculate the pH of the solution. _____ Part 6: (a) Choose the single best answer that describes this solution. _____ (b) Which of the following compounds could be added to the original solution to produce a neutral solution? ___ Part 7: Write the net, balanced, ionic equation for the reaction that will occur when hydrochloric acid is added to the original solution.

Part 1: 0.0552 Part 2: 0.0187 Part 3: 0.0187 Part 4: 5.34 x 10 ^ -13 Part 5: 12.272 Part 6: (a) basic (b) hydrochloric acid Part 7: H^+(aq)+OH^-(aq)→H2O(l)

Ch. Ex. 9 - Identify the species reduced and oxidized during the reaction that occurs in a mercury battery. The reaction of zinc and mercury oxide can be used in the construction of a mercury battery: Zn(s) + HgO(s) ⇌ ZnO(s) + Hg(l) Part 1: In the reaction shown above, zinc ____ electrons while mercury ____ electrons Part 2: (a) Write the chemical formula of the oxidized substance. ____ (b) Write the chemical formula of the reduced substance. ____ Part 3: In the reaction above, Zn is the ____ agent and HgO is the ____ agent Part 4: Using the complete redox reaction as shown below, write the equations for the two half-reactions that occur in a mercury battery. Zn + Hg2+ → Zn2+ + Hg (a) Oxidation Half-reaction: ____ (b) Reduction Half-reaction: ____ Part 5: Mercury batteries were once used to power watches and hearing aids. However, due to the toxicity of mercury, these batteries have been banned. Which of the characteristics below are essential to the design of substitutes for these mercury batteries? Select all answers that apply.

Part 1: loses ; gains Part 2: (a) Zn (b) HgO Part 3: reducing; oxidizing Part 4: (a) Zn→Zn^2++2e^- (b) Hg^2++2e^-→Hg Part 5: Hold charge for many years, Smaller in size, Use metals with reduce toxicity, Lightweight

Ch. Ex. 122 - Oxidation and reduction - write both half-reactions (Pool 2 of 2) Write the oxidation and reduction half-reactions for the following equation. Sr + Pb^2+ → Sr^2+ + Pb Oxidation half-reaction: ____ → ____ Reduction half-reaction: ____ → ____

Sr → Sr^2+ + 2e^- Pb^2+ + 2e^- → Pb