Question

A sample of NO2(g) is initially placed in a 2.50-L reaction vessel at 300°C. If the half-life and the rate constant at 300°C are 33 seconds and 0.54 M-1 s-1, respectively, how many moles of NO2 were in the original sample?

Answer 1

You have to find the density of NO2 at 300°C.
You will get something like (g/cm^3) = (g/ml)
Convert the (g/ml) to (g/L)
Multiple by 2.5 L.
Then you will have the original sample.