H3PO4, which contains three hydrogen atoms per molecule, is a weak acid, whereas HCL, which contains only one hydrogen atom per molecule, is a strong acid. Explain why?
Because based on atomic structure, in hydrogen chloride chlorine has more tendency to gain electron of hydrogen and produce H+ and if hydrogens in phosphoric acid give their electrons to oxygens, there will be repulsion among non-joint electrons pair. Also that is why H3PO4 has acid ionization constant [tex] K_{a} = 7.25*10^{-3}[/tex] and HCl [tex]K_{a}=10^{3}[/tex]. I wish this be helpful for you.