How much heat will be produced when 16grams of C2H6 burns? The reaction is
2 C2H6 + 7 O2 --> 4CO2 + 6 H20 triangle heat = -350kJ
Triangle heat? Ok, the best I can surmise is that the heat of reaction for 2 moles of ethane is -350kJ. Normally, the heat of reaction is specified per mole of either a product or reactant. It is quite sloppy to do other wise.
Assuming 350kJ per 2 moles of ethane, then
using mole mass of ethane as 30g/mole, then heat per gram is 350kJ/60g, multipy this by 16g and you have the heat.
I might note, the author of this problem did not use the published values of the heat of combustion, it is close to 1550kJ/mole for ethane.