Beginner Topic 511 of 1102 Acids, Bases & Electrochemistry
Arrhenius Acids and Bases
Acids produce H+ in water while bases produce OH- ions.
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In-depth explanation of Arrhenius Acids and Bases
Arrhenius defined an acid as a substance that releases hydrogen ions H+ in water and a base as a substance that releases hydroxide ions OH- in water. In aqueous solution neutralization is the combination of these ions to form water, which explains why acid and base solutions cancel each other. The definition is limited to water-based systems, so it cannot explain why ammonia, which contains no hydroxide, behaves as a base. It remains the first model students learn and is still a useful picture for many everyday reactions. Modern theories generalize it to any solvent.
Going deeper: Arrhenius Acids and Bases
Key ideas: Arrhenius acids raise H+ (really H3O+) in water and bases raise OH-. Neutralization is H+ + OH- giving H2O with enthalpy near -57 kJ/mol for strong pairs. Count acidic hydrogens (basicity) and OH groups (acidity) to find equivalents: H3PO4 has three replaceable H, but acetic acid has only one.
Common mistakes and connections: The definition fails for NH3, Na2CO3 and nonaqueous solvents, which is why Bronsted-Lowry and Lewis theories exist. Do not assume every hydrogen in a molecule is acidic: only the O-H of CH3COOH ionizes, not the C-H. Compounds with OH, like CH3OH, are not bases.
Visualization of Arrhenius Acids and Bases
Arrhenius acids raise the hydronium ion concentration in water, shown here as H3O+, the species that H+ really exists as in solution. The interactive lesson shows this as a live animation or chart.
Worked example and use case
HCl dissolves to give H+ + Cl- in water, and NaOH dissolves to give Na+ + OH-.
Frequently asked questions about Arrhenius Acids and Bases
What is Arrhenius Acids and Bases?
Acids produce H+ in water while bases produce OH- ions.
Is Arrhenius Acids and Bases a beginner, intermediate or advanced topic?
Arrhenius Acids and Bases is a beginner topic in Acids, Bases & Electrochemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Arrhenius Acids and Bases?
It is one of the first topics in Acids, Bases & Electrochemistry, so no earlier lesson in this area is required.
What comes after Arrhenius Acids and Bases?
The next topics in Acids, Bases & Electrochemistry are Bronsted-Lowry Theory and Lewis Acids and Bases.
Can I practise Arrhenius Acids and Bases with quizzes?
Yes. The interactive lesson includes a self-check question on Arrhenius Acids and Bases, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Arrhenius Acids and Bases fits in Acids, Bases & Electrochemistry
Arrhenius Acids and Bases is topic 1 of 105 in Acids, Bases & Electrochemistry.