ethanoic acid can be ionized?

CH3COOH cannot completely ionize in water since it is a weak acid (with small Ka).

However, during neutralization, ALL CH3COOH will be neutralized.

There will never be imcomplete ionization of CH3COOH during neutralization. The no. of moles of alkali used in titration is corresponding to the no. of moles of acid in the sample.

Now for the explanation.

The equilibrium of ionization of CH3COOH is:
CH3COOH + H2O ≒ CH3COO- + H3O+
(REACTANTS) (PRODUCT)

(can't type the reversible sign...)

The equation of its neutralization is like this:
CH3COOH + NaOH → CH3COO-Na+ + H2O

試下咁諗,當D alkali同acid react,其實D ionized CH3COOH 會一路少.Equilibrium其中一個特點係當PRODUCT一路少,reactant會一路變做product去補償decrease in amount of product.因為CH3COOH一ionize, alkali就會同佢react, 所以CH3COOH molecules會不停咁ionize直至無哂為止.

ethanoic acid, when dissolved in water, cannot completely ionize. it's a weak acid and can only partially ionize.
the pKa value of ethanoic acid at room conditions is 4.76 ---- by calculations, only 1.3% of acid molecules ionizes in 0.1M solution.

since the ionization process is endothermic, increasing temperature can increase the extent of ionization.

however, the most efficient way to get ethanoic acid completely ionized is to add excess amount of alkali, like sodium hydroxide.

this also answers your second question ---- yes, when dissolved in water, it does not completely ionize.
but when hydroxide is added, H+ is continuously removed. the unionized acid will then get ionized (and neutralized too).
more acid is added, more H+ is neutralized (while the ethanoate ion remains in the solution!), and more acid molecules will be forced to "ionize".

eventually, all acid molecules will be neutralized by the alkali, turning into ethanoate ions and water. "ionization" completes.


therefore, strength of acid/alkali almost has no effect on titrations.
well... maybe you should titrate in slower manner, allowing the unionized molecules to ionize (the process maybe not-too-fast).