How much heat (in kJ) is released or absorbed in the reaction of 10.0 grams of SiO2 (quartz) with excess hydrofluoric acid? You must calculate the enthalpy of the reaction first. 1 SiO 2 (s) + 4 HF (aq) SiF 4(g) + 2 H2O(1) SiF4(g) Enter the VALUE only (and watch your sign).