Average Rate from Concentration-Time Data

Question

For the gas phase decomposition of dinitrogen pentoxide at 335 K

2 N₂O₅4 NO₂ + O₂

the following data have been obtained:

[N2O5], M	0.236	0.151	9.66×10-2	6.18×10-2
time, s	0	95.0	190	285

The average rate of disappearance of N₂O₅ over the time period from t = 190 s to t = 285 s is _____ M s^-1.

Answer 1

Rate of disappearance=change in molarity/change in time

change in molarity=(0.0618 M - 0.0966 M)

change in time=285s - 190s

rate of disappearance=(0.0618 - 0.0966)/(285-190) or -0.000366 M/s