  Inspirals and mergers of black hole (BHs) and/or neutron star (NSs) binaries
are expected to be abundant sources for ground-based gravitational-wave (GW)
detectors. We assess the capabilities of Advanced LIGO and Virgo to measure
component masses using inspiral waveform models including spin-precession
effects using a large ensemble of GW sources {\bf randomly oriented and
distributed uniformly in volume. For 1000 sources this yields signal-to-noise
ratios between 7 and 200}. We make quantitative predictions for how well LIGO
and Virgo will distinguish between BHs and NSs and appraise the prospect of
using LIGO/Virgo observations to definitively confirm, or reject, the existence
of a putative "mass gap" between NSs ($m\leq3\ M_\odot$) and BHs ($m\geq 5\
M_\odot$). We find sources with the smaller mass component satisfying $m_2
\lesssim1.5\ M_\odot$ to be unambiguously identified as containing at least one
NS, while systems with $m_2\gtrsim6\ M_\odot$ will be confirmed binary BHs.
Binary BHs with $m_2<5\ M_\odot$ (i.e., in the gap) cannot generically be
distinguished from NSBH binaries. High-mass NSs ($2<m<3$ $M_\odot$) are often
consistent with low-mass BH ($m<5\ M_\odot$), posing a challenge for
determining the maximum NS mass from LIGO/Virgo observations alone. Individual
sources will seldom be measured well enough to confirm objects in the mass gap
and statistical inferences drawn from the detected population will be strongly
dependent on the underlying distribution. If nature happens to provide a mass
distribution with the populations relatively cleanly separated in chirp mass
space, as some population synthesis models suggest, then NSs and BHs are more
easily distinguishable.
