What is the Ka chemistry constant?

1 Answer
Dec 9, 2016

Answer:

#K_a# is the acid dissociation constant that has been measured for many different acids.

Explanation:

In aqueous solution, an acid dissociates according to the following reaction:

#HA(aq) + H_2O(l) rightleftharpoonsH_3O^+ + A^-#

We can usually measure the extent of this equilibrium by some some means, and thus:

#K_a=([H_3O^+][A^-])/([HA])#

Here, #K_a# is a numerical constant that might be large or small. Strong mineral acids such as #HX, X=Cl, Br, I; H_2SO_4; HClO_4#, have very large acid dissociation constants, and the equilibrium lies strongly to the right. For weaker acids the equilibrium lies to the LEFT. In your text you will probably find a list of weak acids, whose #pK_a# values (#pK_a=-log_10K_a#) have been reported.