Acid-Base Chemistry Quiz
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Questions and Answers

What ions do bases produce when they ionize in water?

  • Oxygen ions (O2-)
  • Hydronium ions (H3O+)
  • Hydroxyl ions (OH-) (correct)
  • Hydrogen ions (H+)

    • Which of the following is a noted shortcoming of the definition of bases?

  • It does not describe their physical properties
  • It includes all non-metal oxides
  • It lacks explanation of acids and bases in non-aqueous media (correct)
  • It requires a presence of water

    • Which option does NOT describe a property associated with bases?

  • They turn litmus paper red (correct)
  • They can ionize to produce hydroxyl ions
  • They taste bitter
  • They feel slippery

    • In aqueous solutions, what is the result of base ionization?

    <p>Production of hydroxyl ions (OH-)</p> Signup and view all the answers

    Why is the study of acid-base equilibria in non-aqueous media important?

    <p>It helps understand chemical reactions in different solvents</p> Signup and view all the answers

    What will be the hydrogen ion concentration in a solution of salts derived from strong acids and bases in pure water?

    <p>$1 imes 10^{-7}$ M</p> Signup and view all the answers

    Which ions do not react with water according to the information provided?

    <p>K+</p> Signup and view all the answers

    What pH value corresponds to the hydrogen ion concentration of $1 imes 10^{-7}$ M?

    <p>pH = 7</p> Signup and view all the answers

    In solutions containing strong acids and bases, where does the hydrogen ion concentration primarily originate?

    <p>From water dissociation</p> Signup and view all the answers

    Which of the following statements is true regarding K+ and Cl- ions in water?

    <p>They do not react with water.</p> Signup and view all the answers

    What is the primary reaction in the Mohr Method for determining Cl- concentration?

    <p>Ag+(aq) + Cl-(aq)  AgCl(s)</p> Signup and view all the answers

    In the Volhard Method, what forms as a result of the reaction between excess Ag+ and SCN-?

    <p>AgSCN(s)</p> Signup and view all the answers

    Which statement about Fajans Titration is correct?

    <p>An adsorption indicator is used in the process.</p> Signup and view all the answers

    What color does dichlorofluorescein exhibit when absorbed on AgCl during Fajans Titration?

    <p>Pink</p> Signup and view all the answers

    In the Volhard Method, what is the role of Fe3+?

    <p>It acts as an indicator forming a red complex.</p> Signup and view all the answers

    What type of ligand is EDTA classified as?

    <p>Hexadentate ligand</p> Signup and view all the answers

    Which of the following statements about the formation constants of EDTA complexes is true?

    <p>Log KMY values can help assess the stability of metal ion complexes.</p> Signup and view all the answers

    How many acid dissociation steps does EDTA have?

    <p>4</p> Signup and view all the answers

    Which of the following metals forms the most stable complex with EDTA based on its log KMY value?

    <p>Fe3+</p> Signup and view all the answers

    What does the term 'a4' refer to in the context of EDTA complex formation?

    <p>The ratio of Y4- to total concentration of EDTA</p> Signup and view all the answers

    Which reaction demonstrates the combination of EDTA with a metal ion?

    <p>Ag+ + Y4- ⇌ AgY3-</p> Signup and view all the answers

    What happens to the concentration of Y4- as pH decreases?

    <p>Y4- concentration decreases</p> Signup and view all the answers

    Which of the following is NOT a form of EDTA?

    <p>Y5-</p> Signup and view all the answers

    What is the concentration of hydroxide ions, [OH-], after adding 1.00 mL of 0.1000M HCl to 100.0 mL of 0.1000M NaOH?

    <p>0.09802M</p> Signup and view all the answers

    What is the pH of the solution after the addition of 1.00 mL of 0.1000M HCl to 100.0 mL of 0.1000M NaOH?

    <p>12.9913</p> Signup and view all the answers

    How do you calculate the concentration of hydronium ions, [H3O+], in the solution?

    <p>[H3O+] = Kw / [OH-]</p> Signup and view all the answers

    Which equation best represents the calculation of [OH-] in the given context?

    <p>[OH-] = (CbVb - CaVa) / (Vb + Va)</p> Signup and view all the answers

    What is the role of Kw in calculating [H3O+]?

    <p>It is the product of concentrations of H+ and OH- at any temperature.</p> Signup and view all the answers

    At the midpoint of a titration of a weak acid with a strong base, what is the relationship between pH and pKa?

    <p>pH = pKa</p> Signup and view all the answers

    What is the initial pH of a 0.1M acetic acid solution before any titration is performed?

    <p>2.8785</p> Signup and view all the answers

    In a titration of 50.0 mL of 0.1 M HOAc with 10.0 mL of NaOH, what is the concentration of acetate ion (OAc-) after this addition?

    <p>0.0167 M</p> Signup and view all the answers

    Which expression correctly describes [H3O+] during the buffer region of the titration?

    <p>[H3O+] = (Ka * [HOAc]) / [OAc-]</p> Signup and view all the answers

    At the equivalence point of the titration, how does the pH compared to 7?

    <p>pH &gt; 7, basic</p> Signup and view all the answers

    What is the formula to calculate the concentration of OAc- at the equivalence point?

    <p>Cs = CbVb / (Va + Vb)</p> Signup and view all the answers

    What determines the pH after the equivalence point in the titration of acetic acid with sodium hydroxide?

    <p>The concentration of excess NaOH</p> Signup and view all the answers

    What can be concluded about the concentration of OAc- at the half-neutralization point?

    <p>It is equal to 0.05 M</p> Signup and view all the answers

    Study Notes

    Acid-Base Equilibria

    • ILOs: Students will learn to calculate pH, evaluate pH values of salts, use the Henderson-Hasselbalch equation, understand buffering capacity, explain polyprotic drugs, calculate pH of solutions with polyprotic species, and construct fractions of polyprotic species as functions of pH.

    Drug Nature and pKa Values

    • Acetyl salicylic acid is an acid with a pKa of 3.49.
    • Benzyl penicillin is an acid with a pKa of 2.76.
    • Ethosunamide is an acid with a pKa of 9.3.
    • Chlorpropamide is an acid with a pKa of 4.8.
    • Sulfadrazine is an acid with a pKa of 6.48.
    • Dephenghydantoin is an acid with a pKa of 8.3.
    • Atropine is a base with a pKa of 9.65.
    • Amphetamine is a base with a pKa of 9.8.
    • Lignocaine is a base with a pKa of 7.9.
    • Procaine is a base with a pKa of 8.8.
    • Tetracycline is a base with pKa values of 3.3, 7.8, and 9.7.

    Acidic Drug Examples

    • Ibuprofen
    • Naproxen
    • Aspirin
    • Nicotinic acid

    Amine-Containing Drugs

    • Labetalol (Trandate)
    • Clobenzorex (Dinintel)
    • Vyvanse (Lisdexamfetamine)
    • Exelon (Rivastigmine)
    • Sensipor (Cinacalcet)
    • Glucagon receptor antagonist (MK-0893)

    Aqueous Solution Equilibria

    • Electrolytes form ions in solution
      • Strong electrolytes are mostly in ionic form
      • Weak electrolytes are mostly not in ionic form
    • Water, methanol, and ethanol are amphiprotic solvents, exhibiting both acidic and basic properties.
    • H2CO3, CH3COOH, and NH3 are amphiprotic solutes
    • Water (2H2O ⇌ H3O+ + OH-) is an amphoteric substance
    • Methanol is an amphoteric substance
    • Glacial acetic acid is an amphoteric substance
      • Some aqueous solutes exhibit both acidic and basic properties

    Acid-Base Theories

    • Arrhenius theory defines acids as substances ionizing in water to release H+ and bases as substances ionizing to release OH-
    • Brønsted-Lowry theory defines acids as proton donors and bases as proton acceptors.

    pH Scale

    • pH = -log[H+]
    • pAnything = -log(Anything)
    • pKw = -logKw at 25°C = 14.00
    • Kw = [H+][OH-]
    • pKw = pH + pOH = 14
    • Blood pH at body temperature (37°C) is typically 7.35-7.45 (slightly basic)

    pH Scale Examples

    • pH of 1M HCl = 0
    • pH of pure water = 7
    • pH of blood = 7.35-7.45
    • pH of 1M NaOH = 14

    Salts of Strong Acids and Bases

    • The pH of the solutions stays constant at 7
    • Ions like Cl- or Na+ do not react significantly with water, keeping the solution neutral

    Weak Acids and Bases

    • Weak acids/bases are partially dissociated in water.
    • The amount dissociated is negligible compared to the original concentration.

    Buffers

    • Buffers resist pH changes upon addition of acid or base.
    • A buffer solution contains a mixture of a weak acid and its conjugate base.
    • Optimal buffering occurs where pH = pKa
    • Buffering capacity = maximum at pH = pKa

    Henderson-Hasselbalch Equation

    • pH = pKa + log [conjugate base]/[acid]

    Polyprotic Acids and Their Salts

    • Polyprotic acids can donate more than one proton, e.g., H3PO4
    • The stepwise dissociation constants for polyprotic acids progressively decrease.

    Titration Curves

    • Titrations are used to determine the concentration of an unknown analyte in a solution
    • Titration curves graph pH vs volume of titrant.
    • The equivalence point is the point at which the titration reaches neutralization
    • Indicators are substances that change color at specific pH ranges, or "equivalence point"

    Acid-Base Color Indicators

    • Organic weak acids/bases that change color over a specific pH range
    • Color change from acid to base form is apparent
    • A high [HIn]/[In-] ratio correlates with color A, while a low [HIn]/[In-] ratio correlates with color B

    Phenolphthalein

    • Weak acid that is colorless in its unionized form, and pink in its ionized form
    • Color change is usually found at pH range 8.2−10.0

    Amino Acids

    • Amino acids are polyprotic
    • Zwitterions are structures with both positive and negative sites.
    • The pI (isoelectric point) is the pH at which the amino acid has a net zero charge.

    Complex Formation Titrations

    • Metal ions form coordination compounds with electron-pair donors (ligands)
    • The coordination number is the number of covalent bonds formed.
    • Chelating ligands (especially multidentate ligands) are preferred for titrations because they form more complete complexes with metal ions

    Chelating Agents

    • Nitrilotriacetic acid (NTA)
    • Ethylenediaminetetraacetic acid (EDTA)
    • Diethylenetriaminepentaacetic acid (DTPA)
    • Trans-1,2-diaminocyclohexanetetraacetic acid (DCTA)
    • Bis-(aminoethyl)glycolether-N,N,N',N'-tetraacetic acid (EGTA)

    EDTA

    • Forms 1:1 complexes with metal ions via 6 ligands (4 O and 2 N)
    • Frequently used in titrations due to its ability to form stable chelates with metal ions.

    Gravimetric Analysis

    • A weighed sample is dissolved
    • A precipitating agent is added to the solution to produce an insoluble precipitate
    • The precipitate is filtered, dried, or ignited, and then weighed
    • The analyte weight % is calculated from the precipitate weight and relevant gravimetric factors.

    Gravimetric Factor (GF)

    • The weight of the analyte per unit weight of precipitate

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    Acid-Base Equilibria PDF

    Description

    Test your knowledge on the properties and theories of bases and acid-base equilibria in aqueous and non-aqueous solutions. This quiz covers key concepts such as ionization, pH values, and specific titration methods important in analytical chemistry.

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