# How to predict whether the aqueous solution for the following salts are acidic , basic or neutral (a)NH4Br (b)KClO4 (c)NaHC2O4 (d)CsBr (e)KHSO4 (f)[CH3NH3]Cl?

Jan 17, 2016

a. acid; b. "neutral"; c. acid; d. "neutral"; e. acid; f. acid
The parent acid, oxalic acid, has $p {K}_{a 1} = 1.25$ and $p {K}_{a 2} = 4.14$. Of course, $p {K}_{a 2}$ is the one that concerns us. Compare $p {K}_{a 2}$ to $p {K}_{a}$ ammonium bromide, $4.76$ (that's from memory, I could not find my old notes, so check on me!). So sodium oxalate is a stronger acid than ammonium bromide, and will thus give also a slightly acidic solution in water.
Another way to look at this is by the strong acid/weak base formalism. Since we are chemists, physical scientists (hopefully!), I would always prefer to get the numbers, and find the $p {K}_{a} ' s$.