Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

A butane burner is used to warm water. The $M_r$ of butane is 58. • $\Delta H_c^{\circ}$ of butane is $-2877\,\text{kJ mol}^{-1}$. • $250\,\text{g}$ of water is heated from $12\,^{\circ}\text{C}$ to $100\,^{\circ}\text{C}$. • The burner transfers $47\%$ of the heat released from the burning fuel to the water. Assume that the butane undergoes complete combustion and none of the water evaporates. What mass of butane must be burnt at minimum?

  • A0.068 g
  • B1.85 g
  • C3.94 g
  • D4.48 g

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