*This is part of an exam. so please don't give full solution* just trying to bump ahead of a block.
The decomposition of NO2 at room temperature exhibits the following variation in concentration with time:
The concentration of NO2 is expressed in mol/liter, while time is expressed in seconds.
[NO2] ln[NO2] 1/[NO2] Time (s)
0.0831 -2.4877 12.03 0
0.0666 -2.7091 15.02 4.2
0.0567 -2.8700 17.64 7.9
0.0487 -3.0221 20.53 11.4
0.0441 -3.1213 22.68 15.0
We have to obtain reaction order.
From my attempts this is not 1st nor 2nd order.
I'm trying with Differential method.
ln (-dC/dt) = alpha * ln(C) + ln(k)
but plotting ln (-dC/dt) vs ln(C) doesn't give a straight line.
???
I think I would try converting concn and time to change in rate and plot change in rate vs concn.
you mean without ln,
just dC/dt over C ?
not a straight line.
I've searched around and I am under the impressione that even if values don't align perfectly people still say it's second order reaction, is it?
ratio of (1/t)/t are as follow:
0.7119
0.7081
0.8257
0.5972
not particularly a straight line, isn't it?
A straight line parallel to x axis is zero order.
A straight line between x and y axis passing through zero is 1 st order (like a Beer's Law plot)
A curved line is second order.
First of all thanks for your help.
I meant that reading around the web, NO2 at room tempearature is said to be a second order rection.
If it was such, the graph of 1/C vs time should be a straight line, whose k is the rate.
I did that, and those values are near but not particularly a straigth line.
ratio of (1/C)/t are as follow:
0.7119
0.7081
0.8257
0.5972
Anyway, starting with first table, so you think this is a second order reaction?
*so, do
Reaction is second order, even if your plot of 1/T doesn't give a perfectly straigth line.
a) 2
b) 0.71
my reagrds to will
To determine the reaction order, you can use the method of initial rates or the method of integrated rate laws. Since you mentioned that you have already attempted the method of initial rates, let's try to use the method of integrated rate laws instead.
The general rate law for a reaction is given by the following equation:
Rate = k[A]^m[B]^n
where [A] and [B] are the concentrations of reactants, k is the rate constant, and m and n are the reaction orders with respect to A and B, respectively.
For the decomposition of NO2, let's consider the following rate law:
Rate = k[NO2]^m
Taking the natural logarithm of both sides, we have:
ln(Rate) = ln(k[NO2]^m)
Using the properties of logarithms, we can rewrite this equation as:
ln(Rate) = ln(k) + m*ln([NO2])
Now, let's consider the given concentration and time data:
[NO2] ln[NO2] 1/[NO2] Time (s)
0.0831 -2.4877 12.03 0
0.0666 -2.7091 15.02 4.2
0.0567 -2.8700 17.64 7.9
0.0487 -3.0221 20.53 11.4
0.0441 -3.1213 22.68 15.0
To determine the reaction order, we can plot ln(Rate) vs ln([NO2]). If the plot is a straight line, it suggests that the reaction follows a specific order with respect to [NO2]. The slope of the line will give us the value of the reaction order.
However, as you mentioned, plotting ln(Rate) vs ln([NO2]) did not give a straight line. In this case, it suggests that the reaction does not follow a simple integer-order reaction (e.g., first order or second order). The reaction may be more complex or may involve multiple steps.
To further analyze the reaction and determine the reaction order, additional data or a different method may be required. It is advisable to consult your course materials, textbooks, or seek guidance from your instructor for further assistance with this specific question.