AS LEVEL CHEMISTRY
TOPIC 4 – ENERGETICS
TEST
Answer all questions
Max 50 marks
Name ……………………………………………………………..
Mark ……../50 ……....% Grade ………
, 1. (a) Explain the meaning of the terms mean bond enthalpy and standard enthalpy of formation.
Mean bond enthalpy .....................................................................................
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Standard enthalpy of formation .....................................................................
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(5)
(b) Some mean bond enthalpies are given below.
Bond N–H N–N N≡N H–O O–O
Mean bond enthalpy/kJ mol –1
388 163 944 463 146
Use these data to calculate the enthalpy change for the following gas-phase reaction
between hydrazine, N H , and hydrogen peroxide, H O
2 4 2 2
+ 2 H––O––O––H N ≡ N + 4 H––O––H
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(3)
TOPIC 4 – ENERGETICS
TEST
Answer all questions
Max 50 marks
Name ……………………………………………………………..
Mark ……../50 ……....% Grade ………
, 1. (a) Explain the meaning of the terms mean bond enthalpy and standard enthalpy of formation.
Mean bond enthalpy .....................................................................................
......................................................................................................................
......................................................................................................................
Standard enthalpy of formation .....................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(5)
(b) Some mean bond enthalpies are given below.
Bond N–H N–N N≡N H–O O–O
Mean bond enthalpy/kJ mol –1
388 163 944 463 146
Use these data to calculate the enthalpy change for the following gas-phase reaction
between hydrazine, N H , and hydrogen peroxide, H O
2 4 2 2
+ 2 H––O––O––H N ≡ N + 4 H––O––H
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
