CHE 202-113 Exam 2 Feb 28 Spring 2018 12) The decomposition of dinitrogen penton
ID: 712868 • Letter: C
Question
CHE 202-113 Exam 2 Feb 28 Spring 2018 12) The decomposition of dinitrogen pentonide is described by the chemic al equation 12) 2 N20S(g) 4 NO2(g) + O2(g) lf the rate of appearance of Oz is equal to 2.40 mol/min at a particular moment, what is the rate of disappearance of N20s at that moment? B) 9.60 mol/min C) 0.600 mol/min D) 1.20 mol/min A) 4.80 mol/min 13) 13) When ethylene glycol, HOCH2CH20H, is added to the water in an automobile radiator, the effect is to A) raise the boiling point and raise the freezing point. B) raise the boiling point and lower the freezing point. C) lower the boiling point and raise the freezing point D) lower the boiling point and lower the freezing point. 14) 14) The first-order reaction, 2 N20) 2N2) O2) has a rate constant equal to 0.76 s-1 at 1000 K. How long will it take for the concentration of N20 to decrease from 1.0 M to .42 M D) 0.88 s B)1.1s C) 24s A) 1.8s 15) 15) A plot of 1/BrO-] vs time is linear for the reaction: What is the order of the reaction with respect to the hypobromite ion, Bro-? A) 0 B) 1 C)2 D) 3 16) The decomposition of ozone in the stratosphere can occur by the following two-step mechanism: 16) BrO + O Br + 02 Which species is a catalyst in this mechanism? A) BrO B) Br C)O D) O3 17) The hydrolysis of tert-butyl chloride is given in the reaction below: 17) CH3)3cci(ag) + H20(r) (CH3)3COH(aq) + H+(aq) + ataq) If the rate law is: Rate k(CH3)3CCIJ what is the order of the reaction with respect to water? A) zero B) first C) second D) thirdExplanation / Answer
Solution
12)
The rate of disappearance of N2O5 = -1/2[N2O5]/dt = the rate of appearance of O2 ([O2]/dt)= 2.40 mol/min
-1/2[N2O5]/dt = 2.40 mol/min
- [N2O5]/dt = 2 x 2.40 mol/min = 4.8 mol/min
Option (A) is correct.
13)
“(B) raise the boiling point and lower the freezing point” is correct.
14)
ln (A0/At) = kt
ln (0.42/1.0) = 0.76 x t
t = ln (0.42) / 0.76
= 0.8675 / 0.76 = 1.14 sec
Option (B) is correct.
15)
The reaction is second order reaction with respect to the hypobromite ion BrO-.
Option (C) 2 is correct.
16) In this reaction, Br is a catalyst. Thus option (B) Br is correct.
17) Reaction is first order reaction. Thus option ‘(B) first’ is correct.
Rate = k[(CH3)3CCl]1