Question

The acidity of ${\mathrm{BF}}_3$can be explained on the basis of one of the following concepts?

• A. Arrhenius concept
• B. Bronsted Lowry concept
• C. Lewis concept
• D. Bronsted Lowry as well as Lewis concept

Answer 1

The correct option is C

Lewis concept

The explanation for the correct option:

• Lewis Acids are the chemical species which have empty orbitals and are able to accept electron pairs from Lewis bases.
• This term was classically used to describe chemical species with a trigonal planar structure and an empty p-orbital
• As per Lewis’s concept, a positively charged or electron-deficient species that can accept a lone pair of electrons is an acid.

The explanation for incorrect options:

Option A:

• According to Arrhenius's theory, acid is a substance that gives H+ ion on dissolving in the aqueous solution.
• It increases the concentration of H+ ions in the solution.
• The base is a substance that ionizes the OH– ion by dissolving it in the aqueous solution.
• The concentration of OH- ions is high in the solution.

Option B:

• According to Bronsted-Lowry theory, acid is a substance which donates an H+ ion or a proton and forms its conjugate base and the base is a substance which accepts an H+ ion or a proton and forms its conjugate acid.

Therefore, the correct option is ‘C’,i.e., the acidity of ${\mathrm{BF}}_3$can be explained on the basis of Lewis's Concept.