Question

From the rate expression for the following reactions, determine their order of reaction and dimensions of the rate constants.
`a. 3NO(g) rarr N_(2)O(g),` Rate`=k[NO]^(2)`
`b. H_(2)O_(2)(aq)+3I^(-)(aq)+2H^(o+) rarr 2H_(2)O(l)+I_(3)^(-),` Rate`=k[H_(2)O_(2)][I^(-)]`
`c. CH_(3)CHO(g)rarr CH_(4)(g)+CO(g),` Rate`=k[CH_(3)CHO]^(3//2)`
`d. C_(2)H_(5)Cl(g) rarr C_(2)H_(4)(g)+HCl(g),` Rate `k[C_(2)H_(5)Cl]`

Answer 1

(i) Given rate = `k[NO]^(2)`
Therefore , order of the reaction = 2
`k = ("Rate")/([NO]^(2))`
Dimension f = `( "mol" L^(-1) s^(-1))/(( "mol" L^(-1))^(2))`
= `("mol" L^(-1) s^(-1))/( mol^(2) L^(-2))`
= `L mol^(-1) s^(-1)`
(ii) Given that = `k [H_(2)O_(2)][l^(-)]`
Therefore , order of the reaction = 2
`k = ("Rate")/([H_(2)O_(2)][I^(-)])`
Dimension of
= `( "mol" L^(-1) s^(-1))/(("mol" L^(-1)) ("mol" L^(-1)))`
= `L mol^(-1) s^(-1)`
Given rate = `k[CH_(3)CHO]^(3//2)`
Therefore , order of reaction = `(3)/(2)`
`k = ( "Rate")/([CH_(3)CHO]^(3/2))`
Dimension of
`( "mol" L^(-1) s^(-1))/(("mol" L^(-1))^((3)/(2)))`
= `("mol" L^(-1) s^(-1))/( mol^((3)/(2)) L^((3)/(2)))`
= `L^((1)/(2)) mol^((1)/(2)) s^(-1)`
(iv) Given rate = k `[C_(2)H_(5)Cl]`
Therefore , order of the reaction = 1
`k = ("Rate")/([C_(2)H_(5)Cl])`
Dimension of
`= ( "mol" L^(-1)s^(-1))/( "mol" L^(-1))`
=` s^(-1)`