Chapter 5, Problem 5.3E

Which system in each pair best represents equilibrium species under standard conditions of temperature and pressure? You may have to apply some basic knowledge of chemistry.

(a) $\text{Rb}$ & ${\text{H}}_{\text{2}}\text{O}$ or ${\text{Rb}}^{+}$ & ${\text{OH}}^{-}$ & ${\text{H}}_{\text{2}}$

(b) $\text{Na}$ & ${\text{Cl}}_{\text{2}}$ or $\text{NaCl}$ (crystal)

(c) $\text{HCl}$ & ${\text{H}}_{\text{2}}\text{O}$ or ${\text{H}}^{+}\left(\text{aq}\right)$ & ${\text{Cl}}^{-}\left(\text{aq}\right)$

(d) $\text{C}\left(\text{diamond}\right)$ or $\text{C}\left(\text{graphite}\right)$