Conjugate Acids and Conjugate Bases
Key Questions
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Answer:
Here is one answer.
Explanation:
See this Socratic answer.
And here's another way to look at it.
A conjugate acid contains one more H atom and one more + charge than the base that formed it.
A conjugate base contains one less H atom and one more - charge than the acid that formed it.
Let us take the example of bicarbonate ions reacting with water to create carbonic acid and hydronium ions.
HCO₃⁻ + H₂O → H₂CO₃ + OH⁻
base + acid → Conj A + Conj BWe see that HCO₃⁻ becomes H₂CO₃. It has one more H atom and one more + charge (-1 + 1 = 0). So H₂CO₃ is the conjugate acid of HCO₃⁻.
The H₂O becomes OH⁻. It has one less H atom and one more – charge. So OH⁻ is the conjugate base of H₂O.
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Acid strength is determined by the amount of that acid that actually ionizes. Acids are molecular covalent compounds which you don't expect to ionize (release an
#H^+# and leave behind the conjugate base, or#Cl^-# for example).The strongest acids ionize 100%. There are 6 that most consider to be the "STRONG" acids: HCl, HI, HBr, HNO_3
#, H_2SO_4# and HClO_4#. These split apart 100%.All other acids are weak acids and ionize to a much lesser amount. For example, acetic acid, like most weak acids, ionizes, 5%.
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All acids have a conjugate base. All bases have a conjugate acid. Acids "donate"
#H^(+)# when they react. This is most easily seen when they dissociate in water:#H_2SO_4# +#H_2O# =>#HSO_4^-# +#H_3O^+# In this example, sulfuric acid (
#H_2SO_4# ) is an acid because it "donates"#H^+# to the water. It becomes the hydrogen sulfite ion (#HSO_4^-# ) which is the conjugate base of sulfuric acid.The same idea applies to a base:
#NH_3# +#H_2O# <=>#NH_4^+# +#OH^-# Ammonia (
#NH_3# ) is a base because is "accepts#H^+# from water to come its conjugate acid, the ammonium ion (#NH_4^+# ).This video gives an overview of acids and bases; the second half is about conjugate pairs:
Simple, easy to understand can be on this site http://www.chemteam.info/AcidBase/Conjugate-Pairs.html