First gather the information about the #DeltaHf# of all the substances
#"substance" color(white)(mmmmm)DeltaHf#
#CO color (white)(mmmmmm)−110.5 kJ·mol^(−1)#
#O_2color (white)(mmmmmmmm) 0 kJ*mol^(-1)#
#CO_2 color (white)(mmmmm)−393.5kJ·mol^(−1) #
Always remember elements have #DeltaHf# as 0
#DeltaH_"rxn" = DeltaH"f of product(s)" - DeltaH"f of reactant(s)"#
If there is a coefficient in front of the substance like C 2CO multiply the #DeltaHf# by the coefficient
#DeltaH_"rxn" = −393.5kJ·mol^(−1) *2 -(−110.5 kJ·mol^(−1) + 0)2#
#DeltaH_"rxn" = −393.5kJ·mol^(−1)*2+110.5 kJ·mol^(−1)*2 #
#DeltaH_"rxn" = -566kJ·mol^(−1)#
This means that the reaction is exothermic.