Acids

Core Concept

  • Binary Acids (-ide): Use the prefix hydro- and change the suffix to -ic (e.g., Chloride becomes Hydrochloric acid).

  • Oxyacids (-ate): Remove the prefix and change the suffix to -ic (e.g., Nitrate becomes Nitric acid).

  • Oxyacids (-ite): Remove the prefix and change the suffix to -ous (e.g., Nitrite becomes Nitrous acid).

  • 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.

Test Yourself

Assorted Multiple Choice
A constant current is passed through an electrolytic cell for 45.0 minutes, delivering a total charge of 8,100 Coulombs. How many moles of electrons were transferred during this process? (Faraday's constant = 96,485 C/mol e⁻)

Podcast Episode

Episode

Acid Nomenclature

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Practice Problems & Worked Out Examples 🔒

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Assorted Multiple Choice

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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.

Video Resources

Whiteboard with notes on naming acids practice problems, including rules for negative ion endings and examples of acids like hydrochloric, nitric, and nitrous acid, with chemical formulas and some handwritten text.
A woman with long dark hair gestures with hands and talks into a camera during a video. Behind her, there is a white door, a white bookshelf, and a lamp on a white cabinet. The video has a red overlay on the right with partially visible text about acids.