Strong / Weak Acids and Bases How can you find if a substance is a: strong acid, weak acid, strong base or weak base?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

Unfortunately the only true way to know is to either consult a list or simply memorize major examples in each category.  Some basic trends are easy enough to memorize and remember, such as all acids based on halogens are strong (like HF, HCl, HBr, HI) and all organic carboxylic acids...

Unlock
This Answer Now

Start your 48-hour free trial to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Start your 48-Hour Free Trial

Unfortunately the only true way to know is to either consult a list or simply memorize major examples in each category.  Some basic trends are easy enough to memorize and remember, such as all acids based on halogens are strong (like HF, HCl, HBr, HI) and all organic carboxylic acids are weak (like acetic acid and formic acid).  But many other examples simply must be remembered.  For example, nitric acid (HNO3) is a strong acid but ammonia (NH3) is a weak base.

One thing to keep in mind, however, is that the conjugate base of a strong acid is a weak base.  Take the example below:

HCl -->  H(+) + Cl(-)

HCl is a strong acid so it will ionize completely in water.  But its conjugate base Cl(-) is a weak base.  So when you dissolve NaCl in water you know that the Cl(-) produced will not act as a strong base.

Approved by eNotes Editorial Team