Which is the stronger acid?

(Hint: You can use the periodic table at the back ofthis book.)

a. HCl or HBr

b. CH₃OH or CH₃SH

c. HF or HCl

d. H₂S or H₂O

a) As we go down the group, the electron cloud becomes larger and there is less attraction on the protons. A proton can easily be removed so that the acid will be stronger.

b) Hybridization = In (Stronger acid hybridization folllows the order sp>sp²>sp³)

c) pK_avalues are as follows: protonated alcohols, protonated carboxylic acids, and protonated water<0; carboxylic acids ~5; protonated amines ~10; alcohols and water ~15.

d)The strength of an acid is determined by the stability of its conjugate base.

e)When atoms are of similar size, the stronger acid is one that has its hydrogen attached to more electronegative elements.

f) Electronegativity = sp>sp²>sp³

g) When atoms are of different size, the stronger acid is one that has hydrogen attached to the largest atom.

Br has a bigger electron cloud than Cl, so Br can easily release the proton. Thus, HBr is a stronger acid.

Sulphur has a bigger electron cloud than oxygen, so sulphur can easily release the proton. Thus, CH₃SH is a stronger acid.

Chlorine has a bigger electron cloud than fluorine, so chlorine can easily release the proton. Hence, HCl is a stronger acid.

Sulphur has a bigger electron cloud than oxygen so sulphur can easily release the proton. Thus, H₂S is a stronger acid.