Chemistry

Chemistry

Problem

Substance X combusts with an enthalpy change of −7.30×102 kJ-7.30\times10^{2}\,\text{kJ} per mole and has a molar mass of 58.0 g mol−158.0\,\text{g mol}^{-1}. Pellet A has twice the mass of pellet B, and both pellets are burned completely under identical conditions. Which statement correctly predicts the comparative heat release? a) Pellet A releases less heat because the negative sign on ΔH\Delta H means the reaction absorbs energy. b) Pellet A releases twice as much heat because doubling the mass doubles the number of moles that react. c) Pellet A releases the same amount of heat because the enthalpy change per mole is constant. d) Pellet A releases half as much heat because larger pellets burn less efficiently, reducing heat per mole.

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