Answer to Question #145056 in General Chemistry for hunter

Question

6. The reaction, 2NO(g) + O2(g) → 2NO2(g), was studied and the following data were obtained.


[NO]0 [O2]0 Initial Rate
(molecules/cm3) (molecules/cm3) (molecules/cm3 s)
1.00 x1018 1.00 x1018 2.00 x1018
3.00 x1018 1.00 x1018 1.80 x1019
3.00 x1018 2.00 x1018 3.60 x1019

What would be the initial rate for an experiment where [NO]0 = 6.21 x 1018 molecules/cm3 and [O2]0 = 7.36 x 1018 molecules/cm3.

Answer 1

To get the order of NO, hold O₂ constant in experiment 1 and 2, you'll notice that as the reactant is tripled, the reaction increases by a factor of 9 which means it is 2nd order in NO

To get the order of O₂, hold NO₂ constant in experiment 2 and 3, you'll notice that as the reactants doubles, the reaction rate also doubles, which means it is 1st order in O₂

Rate = k[NO]²[O₂]

Let's take experiment 1 to find k

2.00 × 10¹⁸ /[ (1.0×10¹⁸ )² (1.0×10¹⁸)] = K

K = 2.0 × 10^-36

R = (2×10^-36)×(6.21×10¹⁸ )² (7.36 ×10¹⁸)

Rate= 5.68 ×10²⁰ molecules/seconds cm³