what are the bondings of acids??

[albertlee]

I think acids are ionically bonded..., but I have never seen solid acids...

 

any help?

 

thx

[RyanJ]

I think acids are ionically bonded...' date=' but I have never seen solid acids...

 

any help?

 

thx[/quote']

 

Not always as far as I remember.

 

Pure Hydrochloric acid, Hydrogen Chloride, is a gas at room temperature.

Pure citric acid is a solid crystalline substance at room temperature

 

So I think there are some ionic ones but again I'm not shure about it but I have seen solid, liquid and gas acids (Or more accuratly the substances that dissolve to form them.)

 

Cheers,

 

Ryan Jones

[albertlee]

thx!~

[woelen]

I think acids are ionically bonded...' date=' but I have never seen solid acids...

 

any help?

 

thx[/quote']

No, acids are not ionic, but covalent. E.g. HCl, HBr, but also H2SO4 are covalent compounds and if they are ionized in the pure state, then it is VERY litte, just as pure water is ionized very little (only 10^(-7) moles per liter).

 

As soon as an acid like HCl or H2SO4 is added to water, then it becomes ionized. So, dissolving an acid HA in water results in the following chemical reaction:

 

HA ---> H(+)(aq) + A(-)(aq) + heat

 

For HCl, HBr, HI, HNO3 and H2SO4 the amount of heat liberated in the ionization reaction is enormous. This is the reason why acids must be mixed with water carefully. Commercial 98% H2SO4 is mostly covalent, but commercial 30% HCl and 65% HNO3 already are ionic (because they are already mixed with water), so mixing of the latter with water does not result in noticeable heatup. However, if you lead gaseous (covalent) HCl through water or add 100% HNO3 to water, then a LOT of heat is produced, just as with H2SO4.

 

With weak acids, the above reaction also occurs, but then the opposite reaction also is important. That is why dissolving of weak acids in water does not release much heat.

 

Now you know that acids are covalent molecular compounds, you can also understand why they have relatively low melting points and boiling points. Acids with a larger molecular weight, however, usually are solids, such as citric acid. Some acids, such as oxalic acid, also are solids, despite their low molecular weight, because they are highly polar and molecules are associated to each other by means of electrostatic forces.