That's great thanks a lot. Just another question please. You know how you said that nitrous acid is weak and so its conjugate base is strong, I read something similar on the internet but didn't really understand it. So is it like whenever we have a weak acid, its CB is strong? And vice versa? And is the same thing applies for bases, so a weak base would have a strong CA?
Thanks
Yes, that's exactly right!
We can come to this conclusion based on how the various acids and bases dissociate. For instance, HCl is a strong acid, completely dissociating into H
+ and Cl
-. Cl
- is the conjugate base of HCl - since HCl dissociates so readily, Cl
- is highly unlikely to accept that H
+ back to form HCl, so it's a very weak base (by the Bronsted-Lowry theory). A similar scenario occurs for strong bases - since a strong base will readily accept a proton, once that proton has been accepted and the conjugate acid is formed, it won't readily 'donate' it back.
A weak acid, on the other hand, will form an equilibrium in water. Take, for example, the fairly weak ethanoic acid, CH
3COOH, which dissociates in water as per the following equilibrium:
CH
3COOH (aq) + H
2O (l) <--> CH
3COO
- (aq) + H
3O
+ (aq)
The conjugate base of CH
3COOH, being CH
3COO
-, is a moderately strong base since it has the tendency to accept a proton back from the hydronium ion and form CH
3COOH again (reverse reaction). A similar thing occurs for a weak base and its conjugate acid.
Hope this clarifies the concept a little more!