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2 marksEnergetics

CSEC Chemistry · January 2011 · Paper 2 · Question 2(b)(iii)

The students conducted a third experiment, Experiment III, to determine the heat of solution of ammonium nitrate by mixing 8 g of ammonium nitrate with 50 cm³ water at room temperature. The temperature before and after the ammonium nitrate was added to the water is given as: Initial temperature = 27°C Final Temperature = 19°C

Calculate the heat change when 8 g of ammonium nitrate is dissolved in 50 cm³ of water. [Relative Atomic Mass: N = 14; H = 1; O = 16; the specific heat capacity of the solution is 4.2 kJ kg⁻¹ K⁻¹; density of water is 1.0 g cm⁻³]

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Other parts of this question

  1. 2(a)(i)What changes would be observed in Beakers A and B over a 24-hour period?[2 marks]
  2. 2(a)(ii)How do the changes in Beaker A differ from that in Beaker B?[1 mark]
  3. 2(a)(iii)Account for any differences in the observations in (a) (ii) above.[3 marks]
  4. 2(b)(i)State whether the process in Experiment III is exothermic or endothermic. The process is[1 mark]
  5. 2(b)(ii)Draw a labelled energy profile diagram to show the heat changes involved in Experiment III.[3 marks]
  6. 2(b)(iv)State ONE assumption necessary in your calculation in (b) (iii) above.[1 mark]
  7. 2(b)(v)From your answer to (b) (iii), calculate the heat change when 1 mole of ammonium nitrate dissolves in water.[2 marks]

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