Dinitrogen tetraoxide, N2O4, and nitrogen dioxide, NO2, exist in dynamic equilibrium with each other - CIE - A-Level Chemistry - Question 2 - 2016 - Paper 1
Question 2
Dinitrogen tetraoxide, N2O4, and nitrogen dioxide, NO2, exist in dynamic equilibrium with each other.
The energy profile for this reaction is shown.
(a) Add labell... show full transcript
Worked Solution & Example Answer:Dinitrogen tetraoxide, N2O4, and nitrogen dioxide, NO2, exist in dynamic equilibrium with each other - CIE - A-Level Chemistry - Question 2 - 2016 - Paper 1
Step 1
Add labelled arrows to the energy profile to indicate the enthalpy change of the reaction, ΔH
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Answer
Draw an arrow vertically upward from the N2O4 line to the 2NO2 line, and label it as ΔH.
Step 2
Add labelled arrows to the energy profile to indicate the activation energy of the forward reaction, Eᵪ
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Answer
Draw an arrow vertically upward from the N2O4 line to the peak of the energy profile, and label it as Eᵪ.
Step 3
Calculate the average molecular mass, Mᵢ, of the resulting equilibrium mixture.
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Answer
To find the average molecular mass, use the formula: Mi=p×Vm
where:
m = mass of the equilibrium mixture = 4.606 g
p = pressure = 1.68 \times 10^{2} , ext{Pa}
V = volume = 1.00 , ext{dm}^3 = 1.00 \times 10^{-3} , ext{m}^3
Now substituting the values: Mi=1.68×102imes1.00×10−34.606extg×831.323=73.6 g mol−1
Step 4
State, in terms of n, the amount, in moles, of NO2 in the equilibrium mixture.
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Answer
The amount of NO2 can be expressed as:
n + 2n = 2n
x = 2n.
