ionisation problem

[martin1106]

For the part ii), the answer says that 'To get back to equilibrium, ionisation of the acid increases causing the [H+] to increase until equilibrium is again established' but I don't understand why the ionisation of the acid would increase.

[rebeccab26]

For the part ii), the answer says that 'To get back to equilibrium, ionisation of the acid increases causing the [H+] to increase until equilibrium is again established' but I don't understand why the ionisation of the acid would increase.

i think 2 is the weak acid as dilution has a greater effect on strong acids
the change would be re-establishing equilibrium

[martin1106]

For the part ii), the answer says that 'To get back to equilibrium, ionisation of the acid increases causing the [H+] to increase until equilibrium is again established' but I don't understand why the ionisation of the acid would increase.

i think 2 is the weak acid as dilution has a greater effect on strong acids
the change would be re-establishing equilibrium

You are right. Yet, i still don't get why [H+] would increase....

[rebeccab26]

For the part ii), the answer says that 'To get back to equilibrium, ionisation of the acid increases causing the [H+] to increase until equilibrium is again established' but I don't understand why the ionisation of the acid would increase.

i think 2 is the weak acid as dilution has a greater effect on strong acids
the change would be re-establishing equilibrium

You are right. Yet, i still don't get why [H+] would increase....

dilution will decrease the [H3O+] ions
pH = -log[H3O+]
Remember that according to Le Chatelier's principle when a change is made the system will more to partially oppose the change
So a decrease in H3O+ through dilution will cause the system to increase the concentration again.
Make sense?

[martin1106]

 Thanks a lot

[daniel034]

I think it's more the addition of water that shifts equilibrium in favour of the forward reaction, as HA + H2O <-> A- + H3O+

[rebeccab26]

I think it's more the addition of water that shifts equilibrium in favour of the forward reaction, as HA + H2O <-> A- + H3O+

either is correct

[LukeHigham]

When the strong acid is ionised, the acid is completely ionised. Dilution of the fully ionised acid only dilute the acid.

For a weak acid HA <-> H+ + A-, (reactant:product = 1:2), a dilution causes the concn of total particles to decrease. According to LCP, a dilution causes the equilm to shift to the side of more particles. So, there s a forward shift and [H3O+] increases (thus the curved increase in graph 2).