Azomethane, CH3NNCH3, is not a stable compound, and once generated, it decomposes. The rate of decomposition was measured by monitoring the partial pressure of azomethane, in torr.
Time (min) 0, 15, 30, 48, 75
Pressure(torr)36.2, 30, 24.9,19.3, 13.1
Determine the instantaneous rate of decomposition of azomethane at t=20 min.
To determine the instantaneous rate of decomposition of azomethane at t=20 min, we need to calculate the rate of change of the partial pressure of azomethane with respect to time at t=20 min. This can be done using the data provided.
First, let's identify the initial and final data points closest to t=20 min. From the given data, the closest time points are 15 min and 30 min.
Time (min) 0, 15, 30, 48, 75
Pressure(torr)36.2, 30, 24.9,19.3, 13.1
Using these two points, we can calculate the average rate of change of pressure with respect to time over this interval:
Average Rate = (P2 - P1) / (t2 - t1)
where P1 and P2 are the pressure values at times t1 and t2, respectively.
In this case, for t=15 min, P1 = 30 torr, and for t=30 min, P2 = 24.9 torr.
Average Rate = (24.9 torr - 30 torr) / (30 min - 15 min)
= (-5.1 torr) / (15 min)
= -0.34 torr/min
The negative sign indicates that the partial pressure of azomethane is decreasing over time.
Therefore, the instantaneous rate of decomposition of azomethane at t=20 min is approximately -0.34 torr/min.