Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

To determine the enthalpy change of combustion of a fuel, an experiment used $1.5\,\text{g}$ ($0.0326\,\text{mol}$) of the fuel to warm $200\,\text{g}$ of water. During the test, the water temperature increased from $25\,^{\circ}\text{C}$ to $55\,^{\circ}\text{C}$. Water has a specific heat capacity of $4.18\,\text{J g}^{-1}\text{K}^{-1}$. A considerable amount of heat is lost in this experiment. As a result, the measured value of the enthalpy change of combustion, $\Delta H_c$, for the fuel will not be the same as the theoretical value. From the information given above, what is the experimental value for the enthalpy change of combustion, $\Delta H_c$, of the fuel?

  • A$-1410\,\text{kJ mol}^{-1}$
  • B$-769\,\text{kJ mol}^{-1}$
  • C$-30.7\,\text{kJ mol}^{-1}$
  • D$-16.7\,\text{kJ mol}^{-1}$

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