4.1 Acids and Bases

LEARNING GOALS

After   Chapter 4.1,    you will    be  able    to:

Recall  the importance  of  amphoteric  species and common  amphoteric  molecules

Describe    the meaning of  pKa and pKb values  in  relation    to  acid    and base    strength

Recall  common  functional  groups  that    act as  acids   or  bases

In an acid–base reaction, an acid and a base react, resulting in the formation of the conjugate base
of the acid and the conjugate acid of the base. This reaction proceeds so long as the reactants are
more reactive, or stronger, than the products that they form. We will discuss acid and base
definitions and strength in the following section. For the MCAT, we will concern ourselves with the
broader Lewis and Brønsted–Lowry definitions of acids and bases. The Lewis definition concerns
itself with the transfer of electrons in the formation of coordinate covalent bonds; the Brønsted–
Lowry definition focuses on proton transfer.

KEY CONCEPT

An  acid–base   reaction    will    only    proceed if  the products    that    will    be  formed  (the    conjugate

base    of  the acid    and the conjugate   acid    of  the base)   are weaker  than    the original    reactants.

DEFINITIONS

A Lewis acid is defined as an electron acceptor in the formation of a covalent bond. Lewis acids
also tend to be electrophiles, which we will touch on in the next section. Lewis acids have vacant p-