Is potassium carbonate a strong base or weak base? Is phospheric acid strong acid or weak acid? What indicator should I use if I want to titrate potassium carbonate with phosphoric acid for complete neutralisation? Also, what pH does that indicator change at? Any alternative indicator? It would be good if you could provide a source.
2007-06-28 01:48:11 · 4 answers · asked by 5 2 in Science & Mathematics ➔ Chemistry
K2CO3 is a salt in which disgregative anions derived from diprotic acid, can be hydrolyze to a considerable extent.
CO32- + H2O <> HCO3- + OH-
Kh= Kw/KII = 1.00 x 10^-14 / 4.84 x 10^-11 = 2.07 x 10^-4
If CO32- is 0.150 M
pH = 11.7 so this strong salt is basic
Phosphoric acid is a weak acid :
H3PO4 <> H+ + H2PO4- KI = 7.5 x 10^-3
H2PO4- <> H+ + HPO42- KII = 6.2 x 10^-8
HPO4- <> H+ + PO43- KIII = 1 x 10^-12
2007-06-28 02:50:10 · answer #1 · answered by Dr.A 7 · 0⤊ 0⤋
If substances have either a Ka or a Kb value that is less than or significantly less than 1, then they are weak acids or bases respectively. Phosphoric acid by definition is a weak acid, but is a much stronger acid than potassium carbonate is a base. A lot will also depend on concentration.
Your endpoint will most likely be in the 4-5 pH range, so you want an indicator which changes in that region and noticeably. There a lot to choose from in that region, but the most common is probably methyl red.
2007-06-28 03:32:54 · answer #2 · answered by TheOnlyBeldin 7 · 1⤊ 0⤋
Is Potassium Carbonate A Base
2016-11-08 00:21:31 · answer #3 · answered by ? 4 · 0⤊ 0⤋
if u wanna know if it is a strong/weak acid/base, u need to find out its pH (or pOH)
pH = -log[H+], it means the less pH is, the stronger acid it is.
pOH = 14 - pH = -log[OH-]
2007-06-28 02:11:08 · answer #4 · answered by medoubleq 2 · 0⤊ 0⤋