  Starting from first principles quantum kinetic theory for ideal plasmas with
exchange effects, the quantum hydrodynamic equations are derived taking moments
of the corresponding exchange-Vlasov equation. The case of an electron-ion
plasma where ions are entirely classical is considered. The linear dispersion
relation for ion-acoustic waves is found from the macroscopic equations and
compared with exchange quantum kinetic theory, yielding a qualitative agreement
apart from a numerical factor of order one in the exchange contribution,
assuming a Maxwellian background as a first step, for analytical simplicity.
The validity conditions of the treatment are discussed and exchange effects are
shown to be necessarily a correction, within the ideal and long wavelength
approximations.
