Question

Give reasons why—
(a) Hydrochloric acid cannot form an acid salt.
(b) Electronegativity increases across a period.

Hint:

Remember: Basicity refers to the number of ionizable H^+ ions in an acid. HCl is monobasic, H_2SO_4 is dibasic, and H_3PO_4 is tribasic!

Answer 1

(a) Basicity of HCl: Hydrochloric acid (HCl) is a monobasic acid. It contains only one ionizable hydrogen atom per molecule (HCl H^+ + Cl^-). Acid salts are only formed by polybasic acids (like H_2SO_4) where there is at least one replaceable hydrogen left after partial neutralization. Since HCl has only one hydrogen, it can only form normal salts.

(b) Nuclear Charge: As we move across a period from left to right, the nuclear charge (number of protons) increases while the number of shells remains the same. This increases the force of attraction exerted by the nucleus on the shared pair of electrons, thereby increasing electronegativity.