[billsauce]

When the reaction
CH3Cl(g) + H2O(g) →CH3OH(g) + HCl(g)
Was studied, the tabulated data were obtained. Based on thesedata, what are the reaction orders?
Initial Concentrations, M; Initial Rates,Ms-1
Exp       CH3Cl      H2O          Rate, Ms-1
1             0.100      0.100           0.182
2           0.200       0.200            1.45
3            0.200       0.400             5.81
A. CH3Cl: firstorder        H2O:first order
B. CH3Cl: second order   H2O: first order
C. CH3Cl: firstorder       H2O: second order
D. CH3Cl: second order   H2O: second order
Please EXPLAIN your answer. why is it  B instead of D??? i know it is first order H2O, but when I calculate the rate for CH3Cl i got 2nd order as well!!!

[Guitarmaniac86]

http://www.chm.davidson.edu/vce/kinetics/MethodOfInitialRates.html

This website should help you.

[billsauce]

the reason this doesnt make sense is because there is no constant for the H2O so i cant get the rate of CH3Cl

[Guitarmaniac86]

I done this:

We know water is second order. (Thats what I calculated anyway)

What happens if we do:

rate1/rate2 = [CHCl3]^a/[CHCl3]^a+[H₂O]^b[H₂O]^b

0.182/1.45=0.01^a/0.02^a+0.01^b/0.02^b

ln 0.126 = ln 0.5a + ln 0.5b

-2.08/-0.69=-0.69a - 0.69b/-0.69

2.99 = a + b

We know b is second order, so we know b=2

3=a+2

a=3-2

Therefore a = 1

I dont know if this is the correct method, however, it makes sense mathematically.

(Incidently, I get the answer as C)

[juanrga]

I done this:

We know water is second order. (Thats what I calculated anyway)

What happens if we do:

rate1/rate2 = [CHCl3]^a/[CHCl3]^a+[H₂O]^b[H₂O]^b

0.182/1.45=0.01^a/0.02^a+0.01^b/0.02^b

ln 0.126 = ln 0.5a + ln 0.5b

-2.08/-0.69=-0.69a - 0.69b/-0.69

2.99 = a + b

We know b is second order, so we know b=2

3=a+2

a=3-2

Therefore a = 1

I dont know if this is the correct method, however, it makes sense mathematically.

(Incidently, I get the answer as C)

How you got

rate1/rate2 = [CHCl3]^a/[CHCl3]^a+[H₂O]^b/[H₂O]^b