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Multiple Choice
Which of the following is a Lewis acid?
A
H2O
B
NH3
C
BF3
D
CH4
Verified step by step guidance
1
Understand the concept of a Lewis acid: A Lewis acid is a chemical species that can accept an electron pair. This is different from a Brønsted-Lowry acid, which donates a proton.
Identify the electron configuration and structure of each molecule: BF3 (boron trifluoride) is a molecule where boron is surrounded by three fluorine atoms. Boron has an incomplete octet, making it electron-deficient and capable of accepting an electron pair.
Analyze the other options: H2O (water) and NH3 (ammonia) both have lone pairs of electrons and typically act as Lewis bases, donating electron pairs rather than accepting them. CH4 (methane) is a saturated hydrocarbon with no ability to accept electron pairs.
Recognize the electron-deficient nature of BF3: Boron in BF3 has only six electrons in its valence shell, making it a classic example of a Lewis acid due to its ability to accept an electron pair to complete its octet.
Conclude that BF3 is the Lewis acid among the given options, as it can accept an electron pair due to its electron-deficient boron atom.