Question

Please explain so that I can understand this concept!

Out of the following two 0.10 M aqueous solution groups, which TWO have the highest pH? (PIck one from EACH grouping)

HNO2
KHCO2
NaI
NH4I
HI


LiOH
KHCO2
NaI
NH4I
HI

(Same thing as above) 0.10M, Pick one out of each grouping- which has the lowest pH?

HI
HF
KNO2
Al(ClO4)3
NH4Br

HF
NaCH3CO2
KNO2
Ca(ClO4)2
NaClO4

Answer 1

The general rules suggest that the stronger of a pair of acids must form the weaker of a pair of conjugate bases. and vice versa.

so we have to use the same concept

by knowing the strength of acids of conjugate bases given.

for 1st

out of all the examples given KHCO2 is the 1 having highset pH as it's acid is HCOOH , which is a weak acid.

2nd

out of all the examples given LiOH is the 1 having highset pH as it's acid is HOH , which is a weaK acid.

3rd

here HI is given which is itself an acid and which is stronger than HF ,(because the atomic radius of an atom of iodine is much larger than that of a Flourine atom.)

4th

HF is given and which iself is an acid , thus it will have lowest pH .