Acid Theories: Arrhenius, Brønsted-Lowry, and Lewis

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What is the definition of an acid according to Arrhenius?

An Arrhenius acid is a substance that increases the concentration of hydrogen ions (H+) in an aqueous solution.

How does the Brønsted-Lowry theory define an acid?

A Brønsted-Lowry acid is a substance that donates a proton (H+) to another substance.

What is the primary feature of a Lewis acid?

A Lewis acid is a substance that can accept an electron pair.

Compare the scope of Brønsted-Lowry acids and Arrhenius acids.

The Brønsted-Lowry definition is more general because it applies to reactions in non-aqueous solvents, unlike Arrhenius.

Give an example of a substance that is a Lewis acid but not a Brønsted-Lowry acid.

Boron trifluoride (BF3) is a Lewis acid but not a Brønsted-Lowry acid because it accepts electron pairs.

Identify a common example of an Arrhenius acid.

Hydrochloric acid (HCl) is a common Arrhenius acid.

How do Brønsted-Lowry acids behave in reversible reactions?

They can donate protons in the forward reaction and accept them in the reverse reaction.

Give an example of a Brønsted-Lowry acid reaction.

In the reaction between NH3 and HCl, HCl donates a proton to NH3.

Explain a scenario where Lewis theory is more applicable than Brønsted-Lowry theory.

Lewis theory is applicable in complexation reactions involving metal ions.

What is a conjugate acid-base pair according to Brønsted-Lowry theory?

It consists of two species that transform into each other by the gain or loss of a proton.

Why is the Lewis definition of acids and bases considered more comprehensive?

It includes reactions that do not involve hydrogen ions or protons.

Describe the key component of a Lewis acid-base reaction.

The reaction involves the transfer of an electron pair from the base to the acid.

What role do acids play in the Arrhenius definition besides increasing H+ concentration?

They decrease the OH- concentration in the solution indirectly by combining with OH- to form water.

How does water act as a Brønsted-Lowry acid?

Water can donate a proton to another water molecule to form hydronium (H3O+) and hydroxide (OH-) ions.

What practical application is influenced by understanding Lewis acids and bases?

Lewis acids and bases play a role in catalysis and the formation of coordination compounds.