Chemistry · Acids, Bases and Salts
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Which of the following can function as Lewis acid?
- A
CN-
- B
NH3
- C
CH3 – O – CH3
- D
I+
The correct answer is I+. A Lewis acid is defined as an electron pair acceptor, and I+ fits this definition because of its positive charge and incomplete octet, making it electron-deficient. This allows it to accept electron pairs from Lewis bases. Other options, such as CN-, NH3, and CH3 – O – CH3, are more likely to donate electron pairs due to their lone pairs or negative charge, making them Lewis bases instead.
The cyanide ion (CN-) has a negative charge, indicating it is more likely to donate an electron pair rather than accept one. It acts as a Lewis base.
Ammonia (NH3) has a lone pair of electrons on nitrogen, making it a good Lewis base, as it tends to donate this pair rather than accept another.
Dimethyl ether (CH3 – O – CH3) has lone pairs on the oxygen, but the molecule is not electron-deficient, so it acts as a Lewis base rather than a Lewis acid.
The iodine cation (I+) is electron-deficient due to its positive charge, making it a good candidate to accept an electron pair, thus acting as a Lewis acid.
Tagged under Chemistry · Acids, Bases and Salts · 2012