chem help please?

Question

An atmospheric chemist fills a gas-reaction container with gaseous dinitrogen pentaoxide to a pressure of 111 kPa, and the gas decomposes to nitrogen dioxide and oxygen. What is the partial pressure of nitrogen dioxide, PNO2, (in kPa) when the total pressure is 187 kPa?

Answer 1

N2O5 -> 2NO2 + 1/2 O2

Let pressure of N2O5 be P

After a certain time, N2O5 left = P(1-x)

NO2 = 2Px

O2 = Px/2

So total pressure = P(1+3x/2) = 187

P = 111

Thus, 111(1+1.5x) = 187

or 1+1.5x = 1.68

or 1.5x = .68

or x = .453

So, PNO2 = 2Px = 2*111*.453 kPa = 100.566 kPa

Answer 2

use the equation....... it s so easy