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When a substance dissolves in water,
the solution may be acidic, neutral or alkaline.
What is an Acid?
Arrhenius
defined an acid is any substance that produces
H+ ions
or H3O+ ions in
water.
Compare this with the definition of an alkali
or base.
H+ ions are called
hydrogen ions,
H3O+ ions are called
hydroxonium ions.
You will mostly see acids in reactions
forming H+
ions.
In reality, H+ is a
single proton, and does not exist on its own.
It always attaches to something.
In
water it joins to H2O to form H3O+ ions.
This
website will use either H+(aq) or H3O+(aq)
to
mean acid in water.
An acid
has a pH of less than 7.
See examples
of acids, properties
of acids and uses
of acids.
See also Lowry and Brønsted.
Links
Acids
Revision Questions
gcsescience.com The Periodic Table Index Acid Quiz gcsescience.com
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