FAD1018: BASIC CHEMISTRY II — Interleaved Mastery Problem Set

4-Day Intensive Study Plan
Topics: Chemical Equilibrium, Ionic Equilibria, Solubility, Kinetics, Electrochemistry, Organic Chemistry, Thermochemistry

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How to Use This Set

Each problem combines 2-4 chemistry topics in realistic contexts. This builds the pattern-recognition skills needed for exams where you must identify which concepts apply.

Study Schedule:

• Day 1: Problems 1-3 (Pharmaceutical & Biochemical contexts)
• Day 2: Problems 4-6 (Environmental & Industrial contexts)
• Day 3: Problems 7-9 (Materials & Energy contexts)
• Day 4: Problems 10-12 (Synthesis & Analysis contexts)

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Chemistry Concepts Relationship Map

graph TD
    A[Chemistry II Concepts] --> B[Chemical Equilibrium]
    A --> C[Ionic Equilibria]
    A --> D[Kinetics]
    A --> E[Electrochemistry]
    A --> F[Thermochemistry]
    A --> G[Organic / Stereochem]
    B --> B1[Le Chateliers Principle]
    B --> B2[van't Hoff Equation]
    C --> C1[Henderson-Hasselbalch]
    C --> C2[Titration Curves]
    D --> D1[Arrhenius Equation]
    D --> D2[Michaelis-Menten]
    E --> E1[Nernst Equation]
    E --> E2[Faradays Law]
    F --> F1[Delta G = Delta H - T Delta S]
    B1 --> H[Problem 1: Blood Buffer]
    C1 --> H
    B2 --> H
    D1 --> I[Problem 3: Battery Degradation]
    E1 --> I
    F1 --> J[Problem 5: Solar Cell]
    E1 --> J
    D1 --> J
    C2 --> K[Problem 12: Titration]
    E1 --> K
    G --> L[Problem 6: Drug Metabolism]
    D2 --> L

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The Mastery Problems

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Problem 1: Blood Buffer System [Equilibrium + Ionic Equilibria + Thermochemistry]

Human blood maintains pH ~7.4 through the carbonic acid/bicarbonate buffer system: $$\text{CO}_2(g) + \text{H}_2\text{O}(l) \rightleftharpoons \text{H}_2\text{CO}_3(aq) \rightleftharpoons \text{H}^+(aq) + \text{HCO}_3^-(aq)$$

Given: $K_{a1}(\text{H}_2\text{CO}_3) = 4.3 \times 10^{-7}$, $\Delta H^\circ = +19.4$ kJ/mol for CO$_2$ dissolution

(a) Calculate the ratio $[\text{HCO}_3^-]/[\text{H}_2\text{CO}_3]$ at blood pH 7.4. [Ionic Equilibria - Henderson-Hasselbalch]

(b) During exercise, body temperature rises from 37°C to 39°C. Using van't Hoff equation, calculate how $K_a$ changes and predict the new pH (assume constant ratio). [Thermochemistry + Equilibrium]

(c) If a patient hyperventilates, removing CO$_2$, predict the equilibrium shift and calculate the new $[\text{H}^+]$ if $[\text{H}_2\text{CO}_3]$ drops by 30%. [Le Chatelier + Equilibrium calculation]

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Problem 2: Aspirin Synthesis & Analysis [Kinetics + Equilibrium + Organic]

Aspirin (acetylsalicylic acid) is synthesized from salicylic acid and acetic anhydride: $$\text{C}_7\text{H}_6\text{O}_3 + \text{C}_4\text{H}_6\text{O}_3 \rightleftharpoons \text{C}_9\text{H}_8\text{O}_4 + \text{CH}_3\text{COOH}$$

The reaction is first-order in each reactant with $k = 2.5 \times 10^{-3}$ M$^{-1}$s$^{-1}$ at 25°C, $E_a = 85$ kJ/mol.

(a) If initial concentrations are 0.10 M each, calculate the initial rate and the time for 50% completion. [Kinetics]

(b) At equilibrium, $K_c = 45$. Calculate the equilibrium conversion percentage starting from stoichiometric amounts. [Chemical Equilibrium]

(c) Aspirin has $pK_a = 3.5$. Calculate the pH of a 0.010 M aspirin solution and the percentage ionized in stomach (pH 2) vs blood (pH 7.4). [Ionic Equilibria]

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Problem 3: Lithium-Ion Battery [Electrochemistry + Thermochemistry + Kinetics]

A Li-ion battery uses: $\text{LiCoO}2$ (cathode) and graphite (anode) $$\text{Li}{1-x}\text{CoO}_2 + x\text{Li}^+ + x\text{e}^- \rightarrow \text{LiCoO}_2 \quad E^\circ = +0.8\text{ V}$$ $$x\text{Li}^+ + x\text{e}^- + \text{C}_6 \rightarrow \text{Li}_x\text{C}_6 \quad E^\circ = -0.2\text{ V}$$

(a) Write the overall cell reaction and calculate $E^\circ_{cell}$, $\Delta G^\circ$, and $K$ at 25°C. [Electrochemistry]

(b) During discharge at 1C rate, the cell voltage drops from 3.7V to 3.5V after 30 minutes. If internal resistance is 0.1Ω, calculate the current and power output. [Electrochemistry + calculations]

(c) The battery degrades via side reaction with $E_a = 95$ kJ/mol. At 45°C (phone heating), how much faster does degradation occur compared to 25°C? [Kinetics - Arrhenius equation]

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Problem 4: Water Treatment Chemistry [Solubility + Equilibrium + Electrochemistry]

Hard water contains Ca$^{2+}$ and Mg$^{2+}$. Water softening uses lime-soda process: $$\text{Ca}^{2+}(aq) + \text{CO}_3^{2-}(aq) \rightleftharpoons \text{CaCO}3(s) \quad K{sp} = 4.8 \times 10^{-9}$$

(a) Calculate the maximum [Ca$^{2+}$] in water with $[\text{CO}_3^{2-}] = 1.0 \times 10^{-4}$ M. Will CaCO$_3$ precipitate if [Ca$^{2+}$] = 2.0 mM? [Solubility Product]

(b) The carbonate comes from dissolved CO$_2$: $\text{CO}_2 + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^- \rightleftharpoons 2\text{H}^+ + \text{CO}3^{2-}$. Calculate $[\text{CO}3^{2-}]$ at pH 8.5 given $K{a1} = 4.3 \times 10^{-7}$, $K{a2} = 5.6 \times 10^{-11}$. [Ionic Equilibria - polyprotic acid]

(c) Electrolysis of brine produces chlorine for water treatment: $2\text{Cl}^- \rightarrow \text{Cl}_2 + 2\text{e}^-$. Calculate the mass of Cl$_2$ produced per hour at 1000 A current. [Electrochemistry - Faraday's law]

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Problem 5: Photovoltaic Cell Materials [Solid State + Electrochemistry + Thermochemistry]

Dye-sensitized solar cells use TiO$_2$ and iodide redox couple: $$\text{I}_3^- + 2\text{e}^- \rightarrow 3\text{I}^- \quad E^\circ = +0.54\text{ V}$$ $$\text{TiO}_2|\text{dye}^+ + \text{e}^- \rightarrow \text{TiO}_2|\text{dye} \quad E^\circ = -0.7\text{ V}$$

(a) Calculate the maximum theoretical voltage and efficiency if the solar input is 1.5 eV photons. [Electrochemistry]

(b) The electron injection from dye to TiO$_2$ occurs in femtoseconds. If the rate constant is $k = 10^{12}$ s$^{-1}$ and $E_a \approx 0$, calculate the temperature range where this remains diffusion-controlled. [Kinetics]

(c) The cell operates at 35°C in sunlight. Calculate $\Delta G$, $\Delta H$, and $\Delta S$ for the overall reaction if $\Delta H^\circ = -120$ kJ/mol. [Thermochemistry]

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Problem 6: Enzyme Kinetics in Drug Metabolism [Kinetics + Organic + Equilibrium]

Cytochrome P450 enzyme metabolizes drug D with Michaelis-Menten kinetics: $K_M = 50$ μM, $V_{max} = 2.0$ μM/min.

(a) Calculate the reaction rate when [D] = 25 μM and when [D] = 200 μM. At what [D] is rate half of $V_{max}$? [Kinetics - Michaelis-Menten]

(b) A second drug competes for the same site with $K_i = 10$ μM. Calculate the apparent $K_M$ at inhibitor concentration 20 μM. [Enzyme inhibition]

(c) The drug exists as two enantiomers. Draw the (R) and (S) forms and predict which the enzyme (chiral active site) will preferentially bind. [Stereochemistry]

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Problem 7: Atmospheric Chemistry [Equilibrium + Kinetics + Thermochemistry]

Ozone formation: $3\text{O}_2(g) \rightleftharpoons 2\text{O}_3(g)$ with $\Delta H^\circ_f(\text{O}_3) = +142.7$ kJ/mol

(a) Calculate $K_p$ at 25°C and predict if ozone is favored at high or low temperature. [Thermochemistry + Equilibrium]

(b) In the stratosphere (220 K, 0.01 atm), calculate $\Delta G$ and the equilibrium O$_3$ partial pressure. [Equilibrium]

(c) Ozone depletion by CFCs: $\text{O}_3 + \text{Cl} \rightarrow \text{O}_2 + \text{ClO}$ ($k = 1.0 \times 10^{12}$ M$^{-1}$s$^{-1}$). Calculate the half-life of O$_3$ at [Cl] = $1.0 \times 10^{-12}$ M. [Kinetics]

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Problem 8: Polymer Synthesis [Organic + Kinetics + Thermochemistry]

Polystyrene is synthesized by free radical polymerization of styrene: $$n\text{CH}_2=\text{CHPh} \rightarrow -(\text{CH}_2-\text{CHPh})_n-$$

(a) Draw the monomer and the head-to-tail polymer structure. Identify the chiral centers in the polymer chain. [Organic - polymer structure]

(b) Initiator decomposition: $k_d = 10^{15}e^{-120000/RT}$ s$^{-1}$. Calculate the half-life at 80°C and 120°C. [Kinetics]

(c) The polymerization is exothermic ($\Delta H = -73$ kJ/mol). Calculate the adiabatic temperature rise if reaction goes to completion in 1 kg styrene ($C_p = 1.7$ J/g·K). [Thermochemistry]

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Problem 9: Metal Corrosion & Protection [Electrochemistry + Equilibrium + Solubility]

Iron corrosion: $\text{Fe} \rightarrow \text{Fe}^{2+} + 2\text{e}^- \quad E^\circ = -0.44$ V with $\text{O}_2 + 2\text{H}_2\text{O} + 4\text{e}^- \rightarrow 4\text{OH}^- \quad E^\circ = +0.40$ V

(a) Write the overall corrosion reaction and calculate $E^\circ_{cell}$ and $\Delta G^\circ$. [Electrochemistry]

(b) In seawater (pH 8.2, [Cl$^-$] = 0.5 M), calculate the actual cell potential using Nernst equation ($P_{\text{O}_2} = 0.21$ atm). [Electrochemistry]

(c) Protective Fe(OH)$2$ forms with $K{sp} = 4.9 \times 10^{-17}$. Calculate [Fe$^{2+}$] at pH 8.2 and determine if precipitation occurs when [Fe$^{2+}$] = $10^{-6}$ M. [Solubility + Equilibrium]

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Problem 10: Amino Acid Chemistry [Organic + Ionic Equilibria + Stereochemistry]

Glycine (H$2$N-CH$2$-COOH) has $pK{a1} = 2.34$ (COOH) and $pK{a2} = 9.60$ (NH$_3^+$).

(a) Draw the fully protonated, zwitterionic, and fully deprotonated forms. Calculate the isoelectric point (pI). [Organic + Ionic Equilibria]

(b) Calculate the concentrations of all glycine species at pH 7.0. What percentage is in the zwitterionic form? [Ionic Equilibria]

(c) Compare with alanine (chiral α-carbon). Draw L-alanine in Fischer projection and assign R/S configuration. Why does the body use L-amino acids exclusively? [Stereochemistry]

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Problem 11: Industrial Ammonia Synthesis [Equilibrium + Kinetics + Thermochemistry]

Haber process: $\text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3$ with $\Delta H^\circ = -92$ kJ/mol, $\Delta S^\circ = -198$ J/mol·K

(a) Calculate $K_p$ at 25°C and 500°C. Why is high temperature used despite lower $K$? [Thermochemistry + Equilibrium]

(b) At 500°C, 200 atm with 1:3 N$_2$:H$_2$, calculate equilibrium NH$_3$ yield. [Equilibrium calculation]

(c) The catalyst (Fe with Al$_2$O$_3$ promoter) reduces $E_a$ from 350 kJ/mol to 100 kJ/mol. Calculate the rate enhancement at 500°C. [Kinetics - Arrhenius]

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Titration Design Flowchart

graph TD
    A[Titration Design] --> B[Standardize NaOH with KHP]
    B --> C{Method?}
    C -->|Potentiometric| D[Use pH meter + glass electrode<br/>E = K + 0.0591 pH]
    C -->|Indicator| E[Choose indicator with<br/>pKa near equivalence pH]
    D --> F[Plot pH vs Volume]
    E --> G[Observe color change]
    F --> H[Equivalence point =<br/>steepest slope / inflection]
    G --> H
    H --> I[Calculate acetic acid<br/>concentration from moles NaOH]

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Problem 12: Analytical Titration Design [Equilibrium + Electrochemistry + Quantitative]

Determine the content of acetic acid in vinegar (density = 1.01 g/mL) using:

• NaOH standardization with KHP
• Potentiometric titration
• pH indicator endpoint

(a) Describe the procedure including calculations for NaOH standardization with KHP (primary standard). [Quantitative analysis]

(b) Sketch the titration curve (pH vs volume) and identify the equivalence point. Calculate pH at half-equivalence and explain its significance. [Ionic Equilibria - titration]

(c) Design a potentiometric method using pH meter. Calculate the expected cell potential at equivalence point if using glass electrode ($E = K + 0.0591$ pH). [Electrochemistry]

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Summary of Techniques Used

Problem	Topics Combined	Context
1	Equilibrium + Ionic + Thermo	Blood buffer
2	Kinetics + Equilibrium + Organic	Drug synthesis
3	Electrochem + Thermo + Kinetics	Battery
4	Solubility + Equilibrium + Electrochem	Water treatment
5	Electrochem + Thermo + Kinetics	Solar cell
6	Kinetics + Organic + Stereochem	Drug metabolism
7	Equilibrium + Kinetics + Thermo	Atmosphere
8	Organic + Kinetics + Thermo	Polymers
9	Electrochem + Equilibrium + Solubility	Corrosion
10	Organic + Ionic + Stereochem	Amino acids
11	Equilibrium + Kinetics + Thermo	Industrial
12	Equilibrium + Electrochem + Quantitative	Analysis

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Key Formulas Reference

Equilibrium

• $K_c = \frac{[products]}{[reactants]}$ (balanced equation)
• $K_p = K_c(RT)^{\Delta n}$
• van't Hoff: $\ln\frac{K_2}{K_1} = -\frac{\Delta H^\circ}{R}(\frac{1}{T_2} - \frac{1}{T_1})$

Ionic Equilibria

• Henderson-Hasselbalch: $pH = pK_a + \log\frac{[A^-]}{[HA]}$
• $pI = \frac{pK_{a1} + pK_{a2}}{2}$ (for amino acids)

Solubility

• $K_{sp} = [\text{ions}]^{\text{stoichiometry}}$
• Ion product $Q$ vs $K_{sp}$ for precipitation prediction

Kinetics

• Arrhenius: $k = Ae^{-E_a/RT}$
• $\ln\frac{k_2}{k_1} = \frac{E_a}{R}(\frac{1}{T_1} - \frac{1}{T_2})$
• Michaelis-Menten: $v = \frac{V_{max}[S]}{K_M + [S]}$

Electrochemistry

• $E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode}$
• $\Delta G^\circ = -nFE^\circ = -RT\ln K$
• Nernst: $E = E^\circ - \frac{RT}{nF}\ln Q$
• Faraday: $m = \frac{MIt}{nF}$

Thermochemistry

• $\Delta G = \Delta H - T\Delta S$
• $\Delta G^\circ = -RT\ln K$

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Related Resources

• Chemical Equilibrium
• Ionic Equilibria
• Solubility Product
• Kinetic Chemistry
• Electrochemistry
• Thermochemistry
• Stereochemistry
• Amines & Amino Acids
• Chemistry Exam Analysis

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#chemistry #interleaved-practice #mastery #fad1018