Which of these three phosphate salts is more acidic?

Question

Im sure it's between a and c ..nd I think its c because of the Hydrogen..but im not sure ..

a) Na3 PO4

b) Na2 HPO4

c) Na H2 PO4

Answer 1

c) Solution of Na H2 PO4 is the most acidic of the 3

Details for Na3PO4 see:

Ex. 1: What is the pH of a 0.20 M solution of Na3PO4?

for Na2HPO4:

Ex. 3: What is the pH of a 0.20 M Na2HPO4 solution?

for NaH2PO4:

Ex. 2: What is the pH of a 0.20 M NaH2PO4 solution?

nearly at the end of this site:

http://www.geocities.com/CapeCanaveral/L...

Answer 2

Since it is the H+ ion that makes it acidic, NaH2PO4 will release more H+ into the solution.