An acid with a small Ka value would be what type of acid?

1 Answer
anor277
Apr 13, 2017

#"A weak acid............"#

Explanation:

The strength of an acid is assessed by the completeness of the following acid dissociation reaction:

#HA + H_2O rightleftharpoonsH_3O^+ + A^-#

And we can write an acid dissociation constant, #K_a#, such that..

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

Given this quotient, if #K_a# is large (or at least #>1)#, then at equilibrium, #[H_3O^+]# is large. See this site. For the stronger acids, #H_2SO_4#, #HClO_4#, #HX (X!=F)#, #HNO_3#, their measured #K_a>=1#.

And for weaker acids, #K_a<1#.

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