Weak Acids and Bases 12.51

[Semi Yoon]

Which acid in each of the following pairs is stronger and explain why: (a) HF or HCl; (b) HClO or HClO2; (c) HBrO2 or HClO2; (d) HClO4 or H3PO4; (e) HNO3 or HNO2; (f) H2CO3 or H2GeO3.

[804991762_4A]

(a) HF or HCl
HCl is a stronger acid because its a binary acid meaning the H is attached to the element and the acid strength increases as you go from the right and down.

(b )HClO or HClO2
HClO2 is stronger because there's more oxygens present. So that means it has a higher Ka value

(c) HBrO2 or HClO2
HClO2 is a stronger acid because its an oxyacid meaning H is attached to the Oxygen and the trend changes, so acid strength increases due to increase in electronegativity

Just apply this trends to the rest of the problems.

[Ray Guo 4C]

Can anyone also explain question (d)? I know that HClO4 is a strong acid and H3PO4 is not, but why is H3PO4 weaker?