What are the values for standard temperature and pressure

Water ionizes by the equation h2o(l)⇌h+(aq)+oh−(aq) the extent of the reaction is small in pure water and dilute aqueous solutions. this reaction creates the following relationship between [h+] and [oh−]: kw=[h+][oh−] keep in mind that, like all equilibrium constants, the value of kw changes with temperature.

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion

What does the symbol (–hfus) indicate in a phase change?