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9701 MCQ Solution 10
Question 10: [Physical
> Chemical Energetics]:
At 600°C oxides of
nitrogen react with un-burnt hydrocarbons in a catalytic converter in a car exhaust.
The equation using methane as representative of a hydrocarbon molecule would be
as follows.
4NO + CH4 à
2N2 + CO2 + 2H2O
Which statement is
likely to be true about the energy change of this reaction?
A It is endothermic as heat energy is converted into
chemical energy.
B It is exothermic as a high temperature is required.
C It is exothermic as the triple bond NO is broken.
D It is exothermic as the products have large negative
enthalpy changes of formation.
Reference: Past Exam Paper – November 2002 Paper 1
Q10
Solution 10:
Answer: D.
A cannot be answer because conversion of energy is not endothermicB cannot be an answer because exothermic reactions do not require a high temperature to start unlike endothermic reactions because exothermic reactions have a smaller activation energy compared to endothermic reactions . Exothermic reactions have s smaller activation energy and therefore do not require high temperature and therefore exothermic reactions occur more readily and at a faster rate than endothermic reactions
C cannot be answer because breaking of a bond is endothermic
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