How do you write an expression for the acid ionization constant (#K_a#) for #HCHO_2#?

1 Answer
Mar 16, 2017

Answer:

#"For formic acid............?"#

Explanation:

We assess the equilibrium:

#H(O=)COH(l) + H_2O(l) rightleftharpoons H(O=)CO^(-) + H_3O^+#

And we write the equilibrium equation in the usual way:

#K_a="Concentration of products"/"Concentration of reactants"#

#K_a=([H(O=)CO^(-)][H_3O^+])/([H(O=)COH(l)])#.

This site reports that #K_a# for formic acid #=1.70xx10^-5#, so it is a weak Bronsted acid.