Why are weak acids like HF acetic acid a strong acid in liquid ammonia

Because in liquid ammonia, nitrogen has strong electronegativity, which is easy to attract hydrogen ions, which in turn aggravates the ionization of hydrogen ions in acetic acid, so that acetic acid changes from weak to strong; In hydrofluoric acid, on the contrary, hydrofluoric acid molecules interact with each other through hydrogen bonds, and this hydrogen bond will also attract -OH on the carboxyl group in acetic acid, so that the solution contains a small amount of OH-, so that acetic acid changes from acid to alkali.

Because liquid ammonia is much more proton-friendly than water, it has been studied as a solvent and is often regarded as a representative of alkaline solvents.

Acid-base reaction in liquid ammonia. The self-dissociation reaction of liquid ammonia is:

2nh3 nh4+ +nh2-

Therefore, the strongest acids and bases in the liquid ammonia system are NH4+ ions and NH2- ions. Since ammonia is more alkaline than water, ammonia's co-choke acid NH4+ is much weaker than that of water's co-choke acid H3O+, while its co-choke alkali NH2- is much stronger than that of water's co-choke alkali Oh-.

Therefore, it is a weakly acidic substance in water and strongly acidic in liquid ammonia.

For example, acetic acid is a weak acid in water, and a strong acid in liquid ammonia, and can be leveled by liquid ammonia solvent to NH4+

Acetic acid (pka= liquid ammonia (pka= liquid hf (pka=.)

Because in liquid ammonia, acetic acid can be completely ionized into the forms of CH2COO- and NH4+.

In liquid HF, because acetic acid is less acidic than liquid HF, it is mainly HF ionization, and acetic acid is used as a weak base to accept H+ ionized by HF

Acetic acid is not very good at hydrogen ion dissociation in water, and acetic acid in water is a weak acid, but in liquid ammonia, due to the similar soluble principle, the degree of ionization of acetic acid is large, which is a strong acid

The answer is supplemented. Take a look at the leveling effect

For non-aqueous solution acid-base problems, it is sufficient to compare the ion product of the liquid state.

Let's take a look at the aqueous solution first, the acids and bases that are usually said exist in the aqueous solution, so the strongest acid in the aqueous solution is H+, and the strongest base is oh-For example, sodium ethanol is more alkaline than sodium hydroxide, but in water, there can be no alkali stronger than OH-.

So, sodium ethanol is converted to OH- and ethanol.

Similarly, HCl, H2SO4, and HCO4 are all completely ionized, so it is impossible to see who is more acidic (these 3 substances can be identified in glacial acetic acid).

Now back to liquid ammonia.

In the same way, the strongest acid is NH4+, (it can also be said to be H+, just like H3O+ in water, but liquid ammonia is generally written NH4+), and the strongest base is NH2-, and the transformation will occur if the strength is exceeded.

For example, acetic acid, which is a weak acid in water, is completely ionized in liquid ammonia, and is a strong acid, hydrochloric acid, and sulfuric acid, not to mention a strong acid.

The alkalinity of sodium hydroxide will become weaker.

It's hard to say how weak it is.

The comparison is based on the ion product of the liquid state.

For example, H+*OH-=10E-14 in water and NH4+*NH2-=10E-34 in liquid ammonia

So if you only look at liquid ammonia, the strong acid in the water is still a strong acid in liquid ammonia, and the weak acid becomes a strong acid, such as carbonic acid, acetic acid, and weak alkali becomes neutral.

If you change to acetic acid as a solvent, the strong acid in the water becomes weak acid, and the weak base becomes strong alkali.