In this work, a u(T,P,I)-QSPR model utilizing the
norm index (I) is developed to predict the speed
of sound (u) of ionic liquids (ILs) over a wide range
of pressures (P) and temperatures (T). During the modeling
process, preprocessing is first performed against the collected data
by using the equipartition rules for temperature and pressure. Temperature
and pressure effects are introduced on the basis of cation, anion,
and IL descriptors. The external and internal validations are used
to evaluate the predictability and robustness of the u(T,P,I)-QSPR model.
The statistical results show that the u(T,P,I)-QSPR model can accurately
predict the u of ILs at variable temperature and
pressure with R
2
test = 0.9952, Q
2
LOCO = 0.9917, and Q
2
LOAO = 0.9903. This facilitates the acquisition
of property data (e.g., density and heat capacity) associated with u and the design of functional ILs.