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Question:

NO2 required for a reaction is produced by the decomposition of N2O5 in CCl4 as per the equation 2N2O5(g) → 4NO2(g) + O2(g). The initial concentration of N2O5 is 3.00 molL⁻¹; and it is 2.75 molL⁻¹ after 30 minutes. The rate of formation of NO2 is :

2.083×10⁻³molL⁻¹min⁻¹

4.167×10⁻³molL⁻¹min⁻¹

8.333×10⁻³molL⁻¹min⁻¹

1.667×10⁻²molL⁻¹min⁻¹

Solution:

Correct option is D. 1.667×10⁻²molL⁻¹min⁻¹
2N2O5(g) → 4NO2(g) + O2(g)
t=0 3.0M
t=30 2.75M
Now, −Δ[N2O5]/Δt = −(2.75−3)/30−0 = 0.25/30 M/min
Again, (1/2)×−Δ[N2O5]/Δt = (1/4)×−Δ[NO2]/Δt
−Δ[NO2]/Δt = 0.25/30 × 2 = 1.66 × 10⁻² M/min