ka for cyanic acid hcno 35 x 10-4 at 25degc

Question

 Ka for cyanic acid (HCNO) =3.5 x 10-4 at 25°C . Write the equilibrium that corresponds to Ka.

The standard heat of combustion of butane gas= - 2.880 x 103 kJ mol-1 at 25 ° C when the products are carbon dioxide gas CO₂ (g) and water H2O (l). compute the value of ΔH ° if the combustion products are CO2 (g) and H2O (g). it isgiven that: CO₂ (g) = ΔHf ° - 393.5 kJmol-1; H₂O (l) = ΔHf ° -285.8 kJmol-1; H₂O (g) = ΔHf ° -241.8 kJmol -1.