Here is a general guide to see if we are faced with strong or weak an acid.
They are strong acids:
- All the hydrogen halides (compounds in which a hydrogen atom is bonded to a halogen) except HF, hydrofluoric acid: HI, HBr, HCl → strong acids
- All oxyacids (compounds with the general formula H x NmeO y) in which the number of oxygen atoms exceeds by two or more the number of acidic protons. For example: H 2 SO 4 → 4 = number of oxygen atoms; number of protons ionizable = 2; difference (nO - nH) = 2
For example: HNO 3, H 2 SO 4, HClO 4 → strong acids
They are weak acids:
- Hydrofluoric acid, HF
- All oxyacids in which the number of oxygen atoms is equal to or exceeds by 1 the number of acidic protons.
For example: H 3 PO 4, HClO, HClO 2, H 3 BO 3 → weak acids
- Much of carboxylic acids (organic acids with the general formula RCOOH)
For example: HCOOH (formic acid), CH 3 COOH (acetic acid), C 6 H 5 COOH (benzoic acid) → weak acids
They have strong bases:
- soluble oxides and hydroxides (compounds containing O 2- or OH -)
This category includes two classes of elements:
The alkali metals, which are the elements of the first group of the periodic table. Damage soluble hydroxides of the general formula Me 2 O, and hydroxides of the formula Me (OH). Oxides and hydroxides of lithium, sodium, potassium, rubidium, cesium → strong bases
The alkaline earth metals, which are the elements of the second group of the periodic table. Damage MeO soluble oxides and hydroxides Me (OH) 2 only strontium, barium and calcium → strong bases
Are weak bases:
- The ammonia and amines.
In general those compounds in which a nitrogen atom (N) exhibits a doublet of not sharing (lone pair) that can accept a proton.