Nuetralization question (1 Viewer)

[Lord Ac]

would 5% HCl require more NaOH for nuetralization than 5% Ch3COOH? Explain your reasoning.

Does the 5% have anything to do with it? Cause i remember the teacher saying once that even though we have weak and strong acid, the same NaOH required ... i Still dont understand that ..

Ac

 

[Toodulu]

whts the 5%? is that concentration?

strong acids would dissociate completely in water, eg. HCL

HCl -> H+ + Cl-

weak acids would only dissociate partly e.g. CH3COOH

CH3COOH -> H+ + CH3COO -

and see how there is still hydrogen in the CH3COO?
and so with the same concentration, the stronger acid would have a higher H concentration because all the H ions are there. in the carbonic acid, some hydrogen ions are still in molecules?

and high [H+] = lower pH

so the HCl will have a lower pH than CH3COOH with the same concentration. ie. more acidic

and so the HCl will require more NaOH to neutralise.

 

[spice girl]

5% is 5% weight / volume

in which case since HCl has a lower molecular mass than CH3COOH, there's a larger number of acidic hydrogens in 5% HCL than in 5% CH3COOH.

When you neutralise, you react acidic hydrogens with a base (in the case of NaOH, the OH-). It's a 1-to-1 ratio, i.e. H+ + OH- -> H2O.

remember acid + base = salt + water?

when you neutralise strong acids you get a neutral salt. when you neutralise weak acids you get a basic salt. This is because the conjugate base of the weak acid is stronger than the conjugate base of the strong acid.

 

[kewpid]

lets say we have 1M NaOH solution

it will be neutralised with 1M HCl and 1M CH3COOH, even though one is a weak acid and one is a strong acid.

this is because as the H+ ions in CH3COOH are neutralised by OH- in NaOH, more H+ ions are ionised into solution (Le Chatelier's principle)

CH3COOH + H2O --> H3O+ + CH3COO-

reduce H+ (coz they react with OH-)
equilibrium will shift to oppose the change
ie. increase H+
the reaction that increases H+ is the reverse reaction

hope that helps