a)
Methane reacts violently with fluorine to form carbon tetrafluoride and hydrogen fluoride
Formulate the equation for this reaction.
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b)
Use your answer to part a) and section 10 of the data booklet to calculate the following:
i)
The energy required, in kJ, to break the bonds for the reaction between methane and fluorine.
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ii)
The energy released, in kJ, to form the bonds for the reaction between methane and fluorine.
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iii)
The enthalpy change, ΔHr , in kJ mol-1 for this reaction.
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c)
A student suggested that one reason for the high reactivity of fluorine is a weak F−F bond. State whether the student is correct. Justify your answer.
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d)
Sketch a labelled energy diagram for the reaction of methane and fluorine.
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a)
Hydrazine has the formula N2 H4 and is used as a rocket fuel (e.g. for the Apollo moon rockets). It burns in the following reaction for which the enthalpy change is -583 kJ mol-1 .
N2 H4 (g) + O2 (g) → N2 (g) + 2H2 O (g)
Sketch the Lewis structure of hydrazine, N2 H4 .
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b)
Use section 11 of the Data booklet and the information in part a) to deduce the bond enthalpy, in kJ mol-1 , for the N-N bond.
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c)
Outline why the value of enthalpy of reaction calculated from bond enthalpies is less accurate.
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