28 Questions
Which type of pair in PYRIDINE is involved in resonance?
sp2
What is the pKa value of the basic pair in PYRROLE?
-0.27
How do electron-donating groups affect base strength?
Strengthen the base
What effect do electron-withdrawing groups have on base strength?
Weaken the base
What percentage of marketed drugs contain functional groups that are ionised at physiological pH?
~85%
What factor differentiates a strong acid from a weak acid in terms of the conjugate base?
Energy level of the conjugate base
Which type of solvation follows ionization in acids?
Endothermic
What factor leads to the stabilization of the conjugate base and makes the acid stronger?
Resonance
Which factor plays a role in stabilizing the conjugate base of an acid based on its electronegativity?
Inductive effects
What process can make the involvement of the lower energy ion (stronger acid) exothermic?
Solvation
In terms of steric effects, what is the general impact on the stabilization of the conjugate base?
Destabilization
What is the pH of the aqueous humour in the body?
7.2
In which part of the body will basic compounds not be well absorbed compared to acidic compounds?
Stomach (fasting)
For a compound with a pKa of 9.4, at what pH will it be 99% ionised?
pH = 5.4
What is the pKa of 2,4-dinitrophenol?
4.1
Where in the body would you find a pH range of 1.4-2.1 in the fasting state?
Stomach (fasting)
What does a small value of pKa for a base indicate?
The base is a weak base.
At what pH will 4-aminopyridine be 50% cationic?
pH = 2.1
How does the presence of an electron withdrawing group affect the basicity of aliphatic amines?
Decreases basicity
Which of the following simple amines has the highest pKa?
Trimethylamine
In the context of bases, what does a large value of Kb indicate?
The base is strong
How does the pKb value relate to the basicity of a cyclic amine?
Lower pKb indicates higher basicity
What effect will destabilize the conjugate base of an acid and make the acid weaker?
Resonance
Which factor can cause major changes in the pKa of a compound?
Resonance
In aliphatic systems, what electron effect do halogens have?
Electron-Withdrawing (-I)
Which effect is generally more influential than inductive effects, except for halides?
Resonance
What property defines the strength of a base?
$Kb$ value
Which value is usually given in literature for bases instead of their $Kb$ values?
$Ka$ value
This quiz covers the concept of electron-donating effects weakening acids. It discusses how various factors such as electronegativity, size, hybridization, resonance, and charge can impact the strength of an acid. Inductive effects are also touched upon as a minor factor.
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