Acids
Related Examples and Practice Problems
Topic Summary & Highlights
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Core Concept
Ionic compounds are composed of a cation and anion. The cation is typically a metal, and the anion is usually a nonmetal or a polyatomic ion (a group of atoms with an overall charge). If the compound contains a metal it is a good sign that it can be considered an ionic compound.
Practice Tips
Memorize Common Polyatomic Ions: Knowing these will make naming oxyacids easier.
Practice with the Endings: Remember, “-ate” becomes “-ic” and “-ite” becomes “-ous.”
Watch for Binary Acids: Recognize binary acids by the “hydro-” prefix.
Acids that do NOT contain oxygen (Binary acids)
hydro______ic acid
The acid name comes from the root name of the anion name. The prefix hydro- and the suffix -ic are then added to the root name of the anion.
Examples:
HBr (aq) → hydrobromic acid
HI (aq) → hydroiodic acid
H₂S (aq) → hydrosulfuric acid
Acid that DO contain oxygen (Oxyacids):
______ic acid or _______ous acid or hypo ______ous acid
⚠️ You need to know your polyatomic ions well. See list here for reference.
Suffixes are used based on the ending of the original name of the oxyanion. If the name of the polyatomic anion ends with: -ate, change it to -ic for the acid
-ite, change it to -ous in the acid … if contains 1 fewer oxygen than “-ate” ion
-ite, change to hypo___ous acid … if contains 2 fewer oxygen than “-ate” ion
Examples:
H₂SO₄ (sulfate is SO₄²⁻) → sulfuric acid
H₂SO₃ (sulfite is SO₃²⁻) → sulfurous acid
HNO₃ (nitrate is NO₃⁻) → nitric acid
HNO₂ (nitrite is NO₂⁻) → nitrous acid
Note: Oxyacids do not use the “hydro-” prefix.
Brain Hack Tip
🧠 Here is a tip of how to remember how to remember how to name acids 🧠
My ride has hydrolics
Ends in “-ide” forms hydro __ic acid
Example: HBr … Br = Bromide, so hydrobromic acid.
I ate something icky
Ends in “-ate” forms __ic acid
Example: HNO3 … NO3- = nitrate, so nitric acid.
Sprite is delicious
Ends in “-ite” forms __ous acid
HNO2 … NO2- is nitrite, so nitrous acid.
