Question

the chemical formulae of some acids are listed in the first column of the table below, and in the second column it says whether each acid is strong or weak. complete the table. list the chemical formula of each species present at concentrations greater than about 10^{-6} mol/l when about a tenth of a mole of the acid is dissolved in a liter of water. acid strong or weak? species present at 10^{-6} mol/l or greater when dissolved in water hclo_{3} strong h_{3}po_{4} weak h_{2}s weak hi strong

Explanation:

Step1: Analyze strong acid \(HClO_3\)

Strong acids completely dissociate in water. The dissociation reaction of \(HClO_3\) is \(HClO_3
ightarrow H^{+}+ClO_3^{-}\). So the species present are \(H^{+}\), \(ClO_3^{-}\).

Step2: Analyze weak acid \(H_3PO_4\)

Weak acids partially dissociate. \(H_3PO_4\) has the following dissociation equilibria: \(H_3PO_4
ightleftharpoons H^{+}+H_2PO_4^{-}\), \(H_2PO_4^{-}
ightleftharpoons H^{+}+HPO_4^{2 -}\), \(HPO_4^{2 -}
ightleftharpoons H^{+}+PO_4^{3 -}\), and water auto - ionizes \(H_2O
ightleftharpoons H^{+}+OH^{-}\). But the main species (concentration \(> 10^{-6}\ mol/L\)) are \(H_3PO_4\), \(H^{+}\), \(H_2PO_4^{-}\).

Step3: Analyze weak acid \(H_2S\)

For \(H_2S\), the dissociation reactions are \(H_2S
ightleftharpoons H^{+}+HS^{-}\), \(HS^{-}
ightleftharpoons H^{+}+S^{2 -}\), and water auto - ionization. The main species (concentration \(> 10^{-6}\ mol/L\)) are \(H_2S\), \(H^{+}\), \(HS^{-}\).

Step4: Analyze strong acid \(HI\)

Strong acid \(HI\) completely dissociates: \(HI
ightarrow H^{+}+I^{-}\). So the species present are \(H^{+}\), \(I^{-}\).

Answer:

acid	strong or weak?	species present at \(10^{-6}\ mol/L\) or greater when dissolved in water
\(H_3PO_4\)	weak	\(H_3PO_4\), \(H^{+}\), \(H_2PO_4^{-}\)
\(H_2S\)	weak	\(H_2S\), \(H^{+}\), \(HS^{-}\)
\(HI\)	strong	\(H^{+}\), \(I^{-}\)