Specific Heat of Gas Mixture in Thermal Quantity Formulas

Yes, the Specific Heat of Gas Mixture, measured in Specific Heat Capacity can be negative.

Specific Heat of Gas Mixture is usually measured using the Joule per Kilogram per K[J/(kg*K)] for Specific Heat Capacity. Joule per Kilogram per Celcius[J/(kg*K)], Kilojoule per Kilogram per K[J/(kg*K)], Kilojoule per Kilogram per Celcius[J/(kg*K)] are the few other units in which Specific Heat of Gas Mixture can be measured.