Final answer:
The correct formula to estimate heat released during burning based on the mass of oxygen consumed is Q = nΔH (option B), which utilizes the moles of oxygen and the enthalpy change per mole of reactant.
Step-by-step explanation:
To estimate the heat released during the burning of a substance based on the mass of oxygen consumed, we must apply the correct formula. The suitable formula in this context, given that we are working with enthalpy changes (denoted as ΔH), is option B) Q = nΔH. This formula uses the number of moles of substance (n) and the enthalpy change per mole (ΔH) to calculate the total heat (Q) released or absorbed during a chemical reaction.
Referring to the combustion of methane as an example, if 1 mol of methane releases 890.4 kJ of heat, then burning 2 moles would release 1781 kJ (2 × 890.4 kJ), and 0.5 mol would release 445.2 kJ (0.5 × 890.4 kJ). By understanding the stoichiometry of the reaction, we can relate this to the mass and moles of oxygen consumed to calculate the total heat released.
Enthalpy changes are significant in understanding exothermic and endothermic reactions. For instance, when methane combusts, it's an exothermic reaction as indicated by the negative enthalpy change. The formula Q = nΔH is built on this understanding of enthalpy to quantify the energy changes in chemical reactions.