Chapter 9 key points
Chemistry 121
Acids and bases
• Brønsted-Lowry definition of an acid: a
substance that dissociates (donates) an H+ ion.
Base: a substance that accepts an H+ ion
• Acids dissociate to form their conjugate bases
• Acid dissociation constant, Ka, measures the
degree of dissociation and therefore strength
• Water has a dissociation constant of 10–14, and
[H+] and [OH–] of a solution are set by that
• pH scale measures the acidity or alkalinity of a
solution
Titrations and buffers
• Salt solutions may be acidic, basic or neutral
• A titration is a quantitative neutralization of
an acid or a base, in order to determine its
concentration
• Indicators are chemicals that change color
depending on the solution’s pH
• Buffers are solution comprising an acid and a
salt of its conjugate base that can resist
changes in pH due to the addition of acids or
bases