Acid ionisation (1 Viewer)

[Yam]

For sulfruric acid, the first hydrogen ion completely dissociates, but what about the second? Does 'di/triprotic' mean that all hydrogen ions completely dissociate?

 

[inasero]

no it means that subsequent ions MAY be able to dissociate...as to the extent you dont know that unless they give u the ionisation constant

 

[toknblackguy]

nope
it just means that the acid has 2/3 hydrogens capable of being donated to a base
but after each ionisation, the successive one becomes harder and harder
after the first complete ionisation of h2so4, it forms an equilbria
HSO4- + H20 <--> H3O+ + SO42-

btw...is it more correct to say ionisatino or dissociation?

 

[inasero]

it doesnt really matter does it? whats the diff?

 

[toknblackguy]

what doesnt really matter?
dissociation and ionisation?
i dunno..that's why i'm asking
i think dissociation is specific to water...meh

 

[Yam]

cool thanks

ionisation and dissociation are basically the same thing arent they? except that molecules ionise and ions dissociate (?)

 

[toknblackguy]

hahaha
frigid..or inasero or someone...clarify
what is ionisation and dissociation

 

[eeyore]

when you're writing equations it's all the same
it's just the arrow....

 

[mercury]

diprotic js means that it has two hydrogens which could become dissociated, ie. pulled off by H2O
in first dissociation, it goes ALL THE WAY, nealry complete

in second dissociation, Ka, the dissociation constant is in the magnitude of 10^-2, so in fact it's stronger than acetic acid(Ka in the magnitude of 10^-5), but it doesn't dissociate completely.

For polyprotic acids, usually, the first dissociation goes the furthest, often nearly ionised to completion. The ones following, second, third dissoication, Ka becomes smaller, so the acids (eg. H2PO4-, HPO4 2-) become weaker and weaker.