2. (4pt) When the concentration of Reactant A is doubled, the reaction rate beco

Question

2. (4pt) When the concentration of Reactant A is doubled, the reaction rate becomes 4 times faster. What is the reaction order of Reactant A? a) 1" order b)2e"order c) 3re order d) one-half1/2) order en one-third l1/3) order n none of the above anced to 'The reas 3. (4pt) What is the most possible unit of the rate constant for the following rate law expression: Rate- k IAI8)? a) 1/min b} M-a seri c) M2 sec-1 d) M. hr'1 e) M-a sec ) none of the above 4. The decomposition reaction of HO, is given by 4 HO g) 2 H2O (gl * 3 Orlg), From the following kinetics data (concentration of HO; vs. time during the reaction) and two figures on right, answer the following questions Time (min) 0.0000 1.2500 2.5000 3.7500 5.0000 (HO.] M (or mol/L) 2.0000 0.66667 0.40000 0.28571 0.22222 In [ HO; ] or Natalie M Question 1 (4pt): The reaction order of should be Hoz order a) First b) Second Neither Question 2 (4pt): Estimate the value of the rate constant of the above decomposition reaction. Show your work. time (min) Ho time (min)

Explanation / Answer

1.Rate is proportional to [A]n where [A] represents the concentration of A.

So if rate is increasing 4 times by increasing the concentration of A 2 times that means n=2 where n=order of reaction so the reaction is 2nd order.(option b)

2.Rate=k[A]3[B]1 k=rate constant

so unit of rate constant = unit of rate /{(concentration)4} = (Msec-1)/{(M)4} = (M)1-4 sec-1 = M-3sec-1

(the options are not showing clearly ) but seeming to be option e

3.if the reaction is to be of 1st order then it should follow the equation

ln{[HO2]0/[HO2]} = kt

ln[HO2]0=kt+ln[H2O]

ln[H2O]=-kt+ln[H2O]0

[HO2]0 And [HO2] represents the concentration of HO2 initially and at any instant respectively.

t=time k=rate constant

so the plot of ln[HO2] vs. t plot is a straight line with negative slope -k and intecept ln[HO2]

Bbut from the picture it can be seen that it is not a straight line with the above conditions.

for 2nd order reaction,

1/[HO2] = 1/[HO2]0-kt

Soplot of 1/[HO2] vs. t should be a straight line with negative slope -k and intercept 1/[HO2]0

SO FROM THE GRAPH WE CAN SEE IT IS SAME .SO THE ORDER OF THE RECATION IS 2ND ORDER.

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