Electron-Donating Effects on Acid Strength Quiz
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Questions and Answers

Which type of pair in PYRIDINE is involved in resonance?

  • sp2 (correct)
  • sp3
  • sp
  • sp3d
  • What is the pKa value of the basic pair in PYRROLE?

  • 5.25
  • 8.75
  • -0.27 (correct)
  • 14.27
  • How do electron-donating groups affect base strength?

  • Have no impact on base strength
  • Strengthen the base (correct)
  • Weaken the base
  • Do not affect the base
  • What effect do electron-withdrawing groups have on base strength?

    <p>Weaken the base</p> Signup and view all the answers

    What percentage of marketed drugs contain functional groups that are ionised at physiological pH?

    <p>~85%</p> Signup and view all the answers

    What factor differentiates a strong acid from a weak acid in terms of the conjugate base?

    <p>Energy level of the conjugate base</p> Signup and view all the answers

    Which type of solvation follows ionization in acids?

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

    What factor leads to the stabilization of the conjugate base and makes the acid stronger?

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

    Which factor plays a role in stabilizing the conjugate base of an acid based on its electronegativity?

    <p>Inductive effects</p> Signup and view all the answers

    What process can make the involvement of the lower energy ion (stronger acid) exothermic?

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

    In terms of steric effects, what is the general impact on the stabilization of the conjugate base?

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

    What is the pH of the aqueous humour in the body?

    <p>7.2</p> Signup and view all the answers

    In which part of the body will basic compounds not be well absorbed compared to acidic compounds?

    <p>Stomach (fasting)</p> Signup and view all the answers

    For a compound with a pKa of 9.4, at what pH will it be 99% ionised?

    <p>pH = 5.4</p> Signup and view all the answers

    What is the pKa of 2,4-dinitrophenol?

    <p>4.1</p> Signup and view all the answers

    Where in the body would you find a pH range of 1.4-2.1 in the fasting state?

    <p>Stomach (fasting)</p> Signup and view all the answers

    What does a small value of pKa for a base indicate?

    <p>The base is a weak base.</p> Signup and view all the answers

    At what pH will 4-aminopyridine be 50% cationic?

    <p>pH = 2.1</p> Signup and view all the answers

    How does the presence of an electron withdrawing group affect the basicity of aliphatic amines?

    <p>Decreases basicity</p> Signup and view all the answers

    Which of the following simple amines has the highest pKa?

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

    In the context of bases, what does a large value of Kb indicate?

    <p>The base is strong</p> Signup and view all the answers

    How does the pKb value relate to the basicity of a cyclic amine?

    <p>Lower pKb indicates higher basicity</p> Signup and view all the answers

    What effect will destabilize the conjugate base of an acid and make the acid weaker?

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

    Which factor can cause major changes in the pKa of a compound?

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

    In aliphatic systems, what electron effect do halogens have?

    <p>Electron-Withdrawing (-I)</p> Signup and view all the answers

    Which effect is generally more influential than inductive effects, except for halides?

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

    What property defines the strength of a base?

    <p>$Kb$ value</p> Signup and view all the answers

    Which value is usually given in literature for bases instead of their $Kb$ values?

    <p>$Ka$ value</p> Signup and view all the answers

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