give examples of 4 strong acids values and 4 strong bases,4 weak acids and 4 weak bases
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CONTENTS
INTRODUCTORY CHEMISTRY – 1ST CANADIAN EDITION
Chapter 12. Acids and Bases
Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Define a strong and a weak acid and base.
Recognize an acid or a base as strong or weak.
Determine if a salt produces an acidic or a basic solution.
Except for their names and formulas, so far we have treated all acids as equals, especially in a chemical reaction. However, acids can be very different in a very important way. Consider HCl(aq). When HCl is dissolved in H2O, it completely dissociates into H+(aq) and Cl−(aq) ions; all the HCl molecules become ions:
HCl → H+(aq) + Cl−(aq) (100%)
Any acid that dissociates 100% into ions is called a strong acid. If it does not dissociate 100%, it is a weak acid. HC2H3O2 is an example of a weak acid:
HC2H3O2→ H+(aq) + C2H3O2−(aq) (~5%)
Because this reaction does not go 100% to completion, it is more appropriate to write it as an equilibrium:
HC2H3O2 ⇄ H+(aq) + C2H3O2−(aq)
As it turns out, there are very few strong acids, which are given in Table 12.2 “Strong Acids and Bases”. If an acid is not listed here, it is a weak acid. It may be 1% ionized or 99% ionized, but it is still classified as a weak acid.
The issue is similar with bases: a strong base is a base that is 100% ionized in solution. If it is less than 100% ionized in solution, it is a weak base. There are very few strong bases (see Table 12.2 “Strong Acids and Bases”); any base not listed is a weak base. All strong bases are OH– compounds. So a base based on some other mechanism, such as NH3 (which does not contain OH− ions as part of its formula), will be a weak base.
Table 12.2 Strong Acids and Bases
Acids Bases
HCl LiOH
HBr NaOH
HI KOH
HNO3 RbOH
H2SO4 CsOH
HClO3 Mg(OH)2
HClO4 Ca(OH)2
Sr(OH)2
Ba(OH)2