Arrhenius Definition:

* An acid is a substance that produces hydrogen ions (H+) when dissolved in water.

* Examples: HCl (hydrochloric acid), HNO3 (nitric acid), H2SO4 (sulfuric acid)

Brønsted-Lowry Definition:

* An acid is a substance that can donate a proton (H+) to another substance (a base).

* This definition is more general than the Arrhenius definition, as it applies to reactions in solvents other than water.

* Examples: HCl, HNO3, H2SO4, as well as organic acids like acetic acid (CH3COOH)

Lewis Definition:

* An acid is a substance that can accept an electron pair from another substance (a base).

* This is the broadest definition, encompassing all acids in the Arrhenius and Brønsted-Lowry definitions, and also including substances that don't contain hydrogen atoms.

* Examples: BF3 (boron trifluoride), AlCl3 (aluminum chloride)

Key properties of acids:

* Sour taste: This is how acids were first identified.

* React with bases to form salt and water: This is known as neutralization.

* Turn blue litmus paper red: This is a classic test for acids.

* Conduct electricity: This is because acids dissociate in water to form ions, which can carry an electrical current.

Important Note: Acids are corrosive and can be dangerous if not handled properly. Always wear protective gear when working with acids, and follow safety protocols.