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Energetics

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Question 26

A student carries out an experiment to investigate the temperature change of water when a sample of anhydrous calcium chloride dissolves in it.

The student obtains the following results:

  • mass of water (mmm) = 75 g75\text{ g}75 g
  • mass of anhydrous calcium chloride added = 6.5 g6.5\text{ g}6.5 g
  • starting temperature of the water = 18.5∘C18.5^\circ\text{C}18.5∘C
  • final temperature of the solution = 34.5∘C34.5^\circ\text{C}34.5∘C
a.

Explain whether the dissolving of anhydrous calcium chloride is exothermic or endothermic.

[2]
b.

Calculate the heat energy change (QQQ), in joules, using the expression:

Q=m×4.2×ΔT Q = m \times 4.2 \times \Delta T Q=m×4.2×ΔT

where ΔT\Delta TΔT is the temperature change.

[2]

Energetics Questions

  1. IGCSE
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  3. /Energetics