IGCSE Chemical Energetics Essay (with the answer key)

 1. Iodine reacts with chlorine to form dark brown iodine monochloride.
                                    

                                                    I2 + Cl2 → 2ICl
(a) Calculate the overall energy change for the reaction between iodine and chlorine using the bond energy values shown.

      Show your working. [3]

(b) Draw a labelled energy level diagram for the reaction between iodine and chlorine using the information in (a). [2]

[Total: 5]

2. Look this reaction.
The reaction is exothermic.

S(g) + 2F2(g)   -->  SF4(g)

(a) Complete the energy level diagram for this reaction. Include an arrow which clearly shows the energy change during the reaction.

(b) During the reaction the amount of energy given out is 780 kJ / mol.
The F–F bond energy is 160 kJ / mol.
Use this information to determine the bond energy, in kJ / mol, of one S–F bond in SF4.

.................................. kJ / mol [3]

[Total: 6]

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