Calculate the enthalpy of reaction at 490 K. You may assume that the heat capacity is constant, and corresponds to the value at 298 K. You may also assume that there are no phase changes in this system (i.e. liquids remain liquids). Note that HNO3 has two forms in the table. The problem assumes that HNO3 is a dissociated electrolyte (ai). 3NO2(g) + H2O (l) -> 2HNO3 (aq) + NO (g).