The calorimetric investigation of the graphite–HNO3–R system (R=CH3COOH, H2SO4) Original Research Article

The interactions of highly oriented pyrolytic graphite with HNO3–R (R=CH3COOH, H2SO4) solution were investigated by Calvet type calorimeter at 305.5 K and X-ray diffraction. It was shown that in the graphite–98% HNO3–100% CH3COOH system the enthalpy of the formation and the stage number of graphite nitrate depends on HNO3 percentage in the solution. Calorimetric investigation of the graphite–98% HNO3–96% H2SO4 system demonstrated that the shape of the heat flow curves corroborates the co-intercalation of HNO3 and H2SO4 into graphite. It was established that the formation of the first stage of ternary compounds of variable composition takes place.