How to know if reaction is endothermic or exothermic?

[eforlano]

Is there a way to know if a reaction is endothermic or exothermic just by looking at the reaction? (no H value) The question shows a series of graphs and then an equation CH4(g) + O2(g) -> CO2(g) + 2H2O(g), and asks which graph could correspond to that particular reaction.

[Hopelesshopefull]

The equation you've given refers to a combustion equation and combustion reactions are exothermic. I guess in this situation they expected u to recognise that O2 was a reactant and that the products of CO2(g) + 2H2O(g) indicate that the reaction is a combustion one, and hence exothermic.
Hope this helps

[eforlano]

Thank you so much you're a massive help