13 The kinetics of the decomposition of dinitrogen pentoxide

13. The kinetics of the decomposition of dinitrogen pentoxide is studied at 50°C and at 75 C t the concentration. It is observed that the rate is higher at the higher temperature. The only correct explaau for this observation among the choices below is: A. The activation energy will be lower at the higher temperature B. The activation energy will be higher at the higher temperature. C. The molecuiles are more disordered at the higher temperature D. A higher proportion of the molocules at the higher temperature have kinetic energies exceeding the acivation energy 14. The equiliberium constant Ke for the reaction, PCly(@)+Clze)e PCIs(e) is 49 at 230°C. Ir0.70 mol of PCly and 0.70 mol of Clh are addled to an evacuated 1.00 L closed reaction vessel at 230°C, the concentration of PClg in moles per liter when equilšbrium has been established is closest to: (you will need to solve a quadratic equation) 0049B.0.1 C.0.30 D.0.59

Solution

13. Answer: D.

by increasing temperature,the kinetic energy of molecules increases.so that,large fraction of molecules exceeds activation energy and involves in reaction.

14.

          PCl3(g) + Cl2(g) <----> PCl5(g)

initial 0.7/1 = 0.7 M 0.7/1 = 0.7 M    0

change    -x            -x             +x

equili   0.7-x         0.7-x            x

Kc = [PCl5]/[PCl3][Cl2]

49 = X/((0.7-X)(0.7-X))

X = 0.59

At equilibrium

[PCl3] = 0.7-0.59 = 0.11 M

answer: B.0.11