[a confused chiral girl]

Hi, I am unsure as to which property is false in describing carboxylic acids.

1. Carboxylic acids with five or fewer carbon atoms quite water-soluble.
2. Carboxylic acids are almost completely dissociated in water.
3. The carbon atom of formic acid, HCOOH, is sp2 hybridized. --> I know that this is true because the C atom is attached with 3 sigma bonds, so it is sp2.
4. The carbon-oxygen bonds of the formate anion (HCOO-) are the same length. --> I know this is true as well, because it's a resonance hybrid which means the bonds have to be same length.

I'm not sure as to whether #1 or #2 is false...
thank you!

[kremar]

1) true. past 5 carbons they start becoming quite non-polar.
2) false. carboxilic acids have pKa's around 4-6 (unless we start adding some EWGs to them, like trifuoroacetic acid which has a pKa of 0.3)

[a confused chiral girl]

Thank you!!

Is dissociation and soluble 2 different things? so since over 5 Carbons mean that it's not as soluble, also means that it's not very dissociating?

[Yggdrasil]

Dissociation and solubility are two different things in general.  Sometimes dissociation and solubility are the same thing, for example, when NaCl dissolves, it dissociates:

NaCl_(s) --> Na⁺_(aq) + Cl^-_(aq)

However, this is true only for ionic compounds.  Covalent compounds do not necessarily need to dissociate in order to disolve.  For example, sucrose (table sugar) is very soluble in water, yet it does not disssociate to any significant extent in neutral water

[brwagur]

At what chain length do carboxylic acids begin to be cosidered fatty acids.

[Yggdrasil]

According to wikipedia, butyric acid is considered to be a fatty acid.    They also note 8 carbons as another cutoff as that's the length of the smallest common fatty acids.

http://en.wikipedia.org/wiki/Fatty_acid

[organoman]

statement 2 is definately false

[wang2033730]

so easy

[HP]

Formic acid is the a strong carboxylic acid - you'll say why...