1) the heat of combustion for the gases hydrogen, methane and ethane are −285.8, −890.4 and −1559.9 kj/mol respectively at 298k.
equation 1 h2 + 1⁄2o2 > h2o δh = −285.8 kj
equation 2 ch4 + 2o2 > co2 + 2h2o δh = −890.4 kj
equation 3 c2h6 + 7⁄2o2 > 2co2 + 3h2o δh = −1559.9 kj

use the above equations to calculate (at the same temperature) the heat of reaction for the following reaction:
2ch4(g) > c2h6(g) + h2(g)
solution: