已知下列反应在标准压力和 298 K 时的反应焓为: ( 1 ) CH 3 COOH ( l ) +2O 2 ( g ) =2CO 2 ( g ) +2H 2 O ( l ) Δ r H m ( 1 ) = - 870.3 kJ·mol -1 ( 2 ) C ( s ) +O 2 ( g ) =CO 2 ( g ) Δ r H m ( 2 ) = - 393.5 kJ·mol -1 ( 3 ) H 2 ( g ) +1/2O 2 ( g ) = H 2 O ( l ) Δ r H m ( 3 ) = - 285.8 kJ·mol -1 则反应:( 4 ) 2C ( s ) +2H 2 ( g ) +O 2 ( g ) =CH 3 COOH ( l )的 = _ ___ 。