Sunday, 9 June 2013

From the rate expression for the following reactions, determine their order of reaction and the dimensions of the rate constants.


From the rate expression for the following reactions, determine their order of reaction and the dimensions of the rate constants.
(i) 3 NO(g) → N2O (g)                                          Rate = k[NO]2
(ii) H2O2 (aq) + 3 I (aq) + 2 H+ → 2 H2O+ (I-) 3 Rate = k[H2O2][I]
(iii) CH3CHO(g) → CH4(g) + CO(g)                     Rate = k [CH3CHO]3/2
(iv) C2H5Cl(g) → C2H4(g) + HCl(g)                      Rate = k [C2H5Cl]
Answer
(i)
Given that
Rate = k [NO]2
Order of the reaction = 2
Use formula

Dimension of rate = mol L-1 s-1
Dimension of concentration = mol L-1
Plug the values
Dimension of k

(ii)
Given that
Rate = k [H2O2] [I]
Order of the reaction = 2
Use formula

Dimension of rate = mol L-1 s-1
Dimension of concentration = mol L-1
Plug the values
Dimension of k

(iii)
Given that
Rate = k [CH3CHO]3/2
Order of reaction = 3/2
Use formula

Dimension of rate = mol L-1 s-1
Dimension of concentration = mol L-1
Plug the values
Dimension of k

(iv)
Given that
Rate = k [C2H5Cl]
Order of the reaction = 1
use formula

Dimension of rate = mol L-1 s-1
Dimension of concentration = mol L-1
Plug the values
Dimension of k


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