Why is #HCl# a stronger acid than #HF#?

1 Answer
James
Jun 26, 2018

#HCl# is a strong acid, while #HF# is a weak acid.

Explanation:

Acid strength refers to how much an acid ionizes when dissolved in water.

In Arrhenius acid-base theory, an acid is a substance which dissolves in water to release one or more #H^+# ions.

A strong acid ionizes completely when dissolved in water. For example, when dissolved in water, every single #HCl# molecule separates into #H^+# and #Cl^-#.

A weak acid only partially ionizes when dissolved in water. For example, when dissolved in water, some #HF# molecules will separate into #H^+# and #F^-#, but some will remain as #HF# molecules.

In the case of #HF#, this behaviour can be attributed to the electronegativity of #F#. The #HF# bond is extremely strong, preventing ionization.

The bond in #HCl# is comparatively weaker, allowing complete ionization.

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