Question

Arrange each group of compounds/ions in order of increasing pH & elaborate why this is so.

a) KBr Na2CO3 Mg(OH)2 HCl

b) SiH4 HI H2S HCl

c) HClO3 HIO IO− HIO3

d) H2O H3O+ OH- HF

e) H2S NaI HCl KOH

Answer 1

a) HCl < KBr <Na2CO3 <Mg(OH)2

reason : Mg(OH)2 is the strong base so more pH and Na2CO3 is the salt of strong base and weak acid so next pH

KBr is the salt of strong acid and strong base so pH = 7 . HCl is strong acid pH <7

b) HI < HCl < H2S< SiH4

central atom electronegativity increases acidity increases and pH decreases

c) HClO3 < HIO3 < HIO < OI-

central atom electronegativity increases acidity increases and pH decreases . and Oi- is basic more pH

d) H3O+ < HF < H2O < OH-

OH- is purely base and more pH . H3O+ is the acid lesser pH

e) HCl < H2S < NaI < KOH

KOH base more pH . NaI neutral salt pH= 7. HCl strong acid less pH