What is the difference between keq and kw

Thanks Mr. I just have one more q'n: Is there any information that can be derived from Kw that can't be derived from the Keq of water? I mean, if a question asks us to use Kw to figure something out, can we substitute Keq of water and instead use 1E -7?

Kw 1e is sometimes not precise enough. Rarely, but it happens, especially when concentration of water is lower that usuall for whatever reason.

In such cases usually activity coefficients are far from 1, which makes calculations much more difficult. Quote from: Jules18 on September 14, , PM. Pages: [ 1 ] Go Up. Sponsored Links. A Lewis base is an electron-pair donor, and a Lewis acid is an electron-pair acceptor. Remember, however, that all three definitions are just different ways of looking at the same kind of reaction: a proton is an acid, and the hydroxide ion is a base—no matter which definition you use. In practice, chemists tend to use whichever definition is most helpful to make a particular point or understand a given system.

Recall that because of its highly polar structure, liquid water can act as either an acid by donating a proton to a base or a base by using a lone pair of electrons to accept a proton.

Water is thus termed amphiprotic, meaning that it can behave as either an acid or a base, depending on the nature of the other reactant. Because water is the solvent, and the solution is assumed to be dilute, the activity of the water is approximated by the activity of pure water, which is defined as having a value of 1.

The activity of each solute is approximated by the molarity of the solute. In this reaction, one water molecule acts as an acid and one water molecule acts as a base. Thus the number of dissociated water molecules is very small indeed, approximately 2 ppb. In pure water, the concentrations of the hydronium ion and the hydroxide ion are equal, and the solution is therefore neutral.

Because the scale is logarithmic, a pH difference of 1 between two solutions corresponds to a difference of a factor of 10 in their hydronium ion concentrations. Recall also that the pH of a neutral solution is 7.