Which is a strong acid?
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Correct Answer: B. H2SO4
A strong acid must be able to provide large numbers of hydrogen ions when dissolved in water, (H+(aq)). Thus a strong acid must dissociate (break into ions) completely upon dissolving in water to provide as many H+(aq) ions as possible.
All these compounds are water soluble, but only CH3CH2COOH and H2SO4 can provide H+(aq) ions. CH3CH2COOH or propanoic acid, is only partially dissociates (<1%) in water and is thus a weak acid. H2SO4 or sulfuric acid, completely (100%) dissociates into sulfate ions and hydrogen ions upon dissolving in water and is thus the strong acid of the group.
CH3CH2OH – ethanol does not dissociate, but stays as a complete molecule in solution.
NH4OH – ammonium hydroxide, a weak base which partially dissociates to give few hydroxide OH–(aq) ions.
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