Oxidation Reactions in Titrations
8 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What color change indicates the endpoint in a titration involving KMnO₄?

  • Colorless to yellow
  • Purple to colorless (correct)
  • Green to blue
  • Colorless to purple

    • Which statement is true regarding potassium dichromate (K₂Cr₂O₇)?

  • It requires external indicators for titration. (correct)
  • It is a stronger oxidizing agent than KMnO₄.
  • It can oxidize I⁻ to I₂ without additional agents.
  • It serves as a self-indicator.

    • What reaction occurs during iodimetric titrations involving Cu²⁺ ions?

  • 2Cu²⁺(aq) + 4I⁻(aq) → Cu₂I₂(s) + I₂(aq) (correct)
  • I₂(aq) + 4H⁺(aq) + 2e⁻ → 2I⁻(aq) + 2H₂O(l)
  • Cu²⁺(aq) + I₂(aq) → CuI₂(s)
  • I₂(aq) + S₂O₃²⁻(aq) → Na₂S₄O₆(aq) + 2I⁻(aq)

    • What is the equivalent weight of KMnO₄ when used in acidic medium?

    <p>31.6 g</p> Signup and view all the answers

    Which oxidizing agent is used specifically for titrating strong reducing agents like sodium thiosulphate?

    <p>Iodine (I₂)</p> Signup and view all the answers

    What role does freshly prepared starch solution play in iodimetric titrations?

    <p>It forms a blue complex with iodine for endpoint detection.</p> Signup and view all the answers

    Which oxidizing agent is characterized as a self-indicator?

    <p>Potassium permanganate (KMnO₄)</p> Signup and view all the answers

    In iodimetric titrations, released iodine (I₂) is titrated against which solution?

    <p>Sodium thiosulphate (Na₂S₂O₃)</p> Signup and view all the answers

    Study Notes

    Oxidation Reactions as the Basis of Titrations

    • Potassium permanganate (KMnO4) is a strong oxidizing agent
    • In titrations, KMnO4 acts as a self-indicator; its color disappears when it reacts with a reducing agent.
    • The reaction for the titration of MnO4- against Fe2+ ions is: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
    • Acidified potassium dichromate (K2Cr2O7) is a weaker oxidizing agent than KMnO4
    • It does not act as a self-indicator; indicators like diphenylamine or potassium ferricyanide (K3[Fe(CN)6]) are used
    • The chemical equation for K2Cr2O7 as an oxidizing agent is: Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O

    Iodine (I2)

    • Iodine is a mild oxidizing agent
    • The reaction is: I2 + 2e- → 2I-
    • Iodine is used in titrations with strong reducing agents like sodium thiosulfate (Na2S2O3)
    • The reaction is: I2(aq) + 2S2O32-(aq) → 2I-(aq) + S4O62-(aq)

    Iodimetric and Iodometric Titrations

    • Iodimetric titrations: Iodine (I2) is directly titrated against a reducing agent
    • Iodometric titrations: Iodine is liberated from KI by an oxidizing agent, and the liberated iodine is then titrated against a standard solution of sodium thiosulfate (Na2S2O3)
    • The end point of iodimetric titrations is detected using a starch solution, which reacts with iodine to form an intensely blue-colored complex

    Note

    • Equivalent weight (Eq. wt.) of an oxidizing or reducing agent = Mol. wt / Change in oxidation state or number of electrons gained or lost
    • Example: Eq. wt. of KMnO4 in an acidic medium = 158/5 = 31.6

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Explore the fundamentals of oxidation reactions as they apply to titrations, highlighting the role of strong oxidizing agents such as potassium permanganate and potassium dichromate. Understand the self-indicating properties of KMnO4 and the use of indicators with K2Cr2O7. This quiz will test your knowledge of these important chemical processes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser