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1 markEnergetics

CSEC Chemistry · January 2018 · Paper 2 · Question 4(a)(ii)

When a reaction is accompanied by energy changes, it can be categorized as either endothermic or exothermic.

Generally, when chemical reactions take place, existing bonds are broken and new bonds are formed. Classify bond making AND bond breaking as either endothermic or exothermic processes.

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Other parts of this question

  1. 4(a)(i)Distinguish between the terms 'endothermic' and 'exothermic.'[2 marks]
  2. 4(b)(i)Calculate the number of moles of KNO₃ used in the experiment. (RMM: KNO₃ = 101)[1 mark]
  3. 4(b)(ii)Calculate the heat change for the reaction. Specific heat capacity of water = 4.2 J g⁻¹ °C⁻¹; Heat change = m × c × △T; Density of water = 1 g cm⁻³[2 marks]
  4. 4(b)(iii)Calculate the enthalpy change for 1 mole of potassium nitrate.[1 mark]
  5. 4(b)(iv)List TWO pieces of apparatus necessary to conduct the experiment in a school laboratory. State how EACH piece of apparatus is used.[4 marks]
  6. 4(b)(v)Draw a labelled energy profile diagram to represent the enthalpy change for the reaction. On your diagram, indicate the sign of △H for the reaction.[3 marks]

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