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Energetics

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Question 31

To determine the heat energy released during a neutralisation reaction, a student mixes a solution of lithium hydroxide with hydrobromic acid in a polystyrene cup. The student records the following data:

  • Volume of lithium hydroxide solution = 65.0 cm365.0\text{ cm}^365.0 cm3
  • Volume of hydrobromic acid solution = 85.0 cm385.0\text{ cm}^385.0 cm3
  • Initial temperature of both solutions = 18.2∘C18.2^\circ\text{C}18.2∘C
  • Highest temperature reached by the mixture = 32.6∘C32.6^\circ\text{C}32.6∘C

Calculate the heat energy released, in joules (J\text{J}J), using the equation:

Q=m×4.18×ΔT Q = m \times 4.18 \times \Delta T Q=m×4.18×ΔT

where:

  • QQQ is the heat energy released in J\text{J}J
  • mmm is the mass of the mixture in g\text{g}g
  • ΔT\Delta TΔT is the change in temperature in ∘C^\circ\text{C}∘C

Assume that the density of the mixture is 1.00 g cm−31.00\text{ g cm}^{-3}1.00 g cm−3, so that 1.00 cm31.00\text{ cm}^31.00 cm3 of the mixture has a mass of 1.00 g1.00\text{ g}1.00 g.

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Energetics Questions

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