# URGENT CHEM HELP

hey guys,

i am havign trouble answering come homework problems. do you think i can get some help?

1. The rate at which tree crickets chirp is 190 1/min at 28 oC but only 39.6 1/min at 5 oC. Calculate the "energy of activation" for the chirping process. One of the forms of the Arrhenius equation from the text is ln(k2/k1) = (Ea/R)(1/T1-1/T2), where R = 8.3145 J/(mol*K).

2. Do the following for the ozone decomposition mechanism: 2O3---->  3O2

a. Express the rate in terms of O2 formation.
rate = _____ ?[O2]/?t

b. Relate the rate of O3 consumption to the rate of O2 production.
?[O3]/?t = _____ ?[O2]/?t

c. If O2 forms at a rate of 2.7E-6 M/s, state how fast ozone disappears.

The rate constants will be directly proportional to the rates.  Thus k1/k2 = Rate1/Rate2.

Once you know the ratio of the rates you can plug the various values into Arrhenius's equation and it becomes a algebra problem of solving for Ea.  I came up with a value of around 7 kJ/mol.

For 2a) The rate of the reaction in terms of O2 formation would be:
rate = __1_ ?[O2]/?t
For 2b) The rate of the reaction in terms of O3 consumption would be:
?[O3]/?t = __3/2 x___ ?[O2]/?t

For 2b) Use the relationship in 2b to calculate the answer.

i am still having trouble solving both problems.

for number 1 my values are too high.

and for question 2 my values are negative and incorrect.

You need to show me what you've done.  I told you how to do it above, so show me how you are applying what I told you and I'll try to figure out where you are going wrong?

For instance, what was the ratio of Rate1 to Rate2?
Show me how you plugged into the Arrhenius equation. etc.