At high concentrations of [H2] the observed rate law is found to change to the form: Rate = k[NO]^2 i.e. the rate becomes independent of [H2].
1. Assess whether the two step mechanism:
H2 + 2NO → N2 + H2O + O (k1)
O + H2 → H2O (k2)
can explain this additional data.
Reexamine the mechanism:
2NO + H2 → O + H2O + N2 (slow k1)
O + H2 → H2O (k2)
2. Write the forward rates for both steps.
3. Based on these rates, would you expect the mechanism to change as [H2] increases? (Hint: look at the ratio)
4. Can this mechanism give the rate law Rate = k[NO]2 observed at high [H2]?
5. What other aspect of this two step mechanism might make it less likely to be the correct mechanism?
0 answers