Finding First Order Rxn Rate Constant

AI Thread Summary
The discussion focuses on calculating the rate constant for a first-order reaction involving an acid solution and a ferrous complex. The user has a slope of -0.008 from a graph of ln optical density versus time, suggesting a rate constant (k) of 0.008. However, there is confusion regarding the concentration of the reactant [A] needed for the rate equation R = k[A]. The user is uncertain about how to apply the absorbance formula A = E*l*c to determine [A]. Ultimately, the rate constant is confirmed as k = 0.008/min, but further clarification on [A] is needed for complete understanding.
BayernBlues
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Homework Statement



I have a first order reaction where I need to find the rate constant. I have the following data:
T = 30'C
the slope of a graph with ln O.D vs T (minutes) is -0.008 so k is 0.008.

The Attempt at a Solution



I'm unsure about what reaction I would need here. This is for an acid sol'n (1 M H2SO4) mixed with a ferrous complex in a spectrophotometer with a 510 nm wavelength. I know there's the formula A = E*l*c where E is epsilon but I don't know how to determine the first order rate constant from this. For first order rate reactions: R = k[A] I know that k is 0.008 but I don't know how to get [A]
 
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Isn't the rate constant simply k=0.008/min?
 
Thread 'Confusion regarding a chemical kinetics problem'

Thread 'Confusion regarding a chemical kinetics problem'

TL;DR Summary: cannot find out error in solution proposed. [![question with rate laws][1]][1] Now the rate law for the reaction (i.e reaction rate) can be written as: $$ R= k[N_2O_5] $$ my main question is, WHAT is this reaction equal to? what I mean here is, whether $$k[N_2O_5]= -d[N_2O_5]/dt$$ or is it $$k[N_2O_5]= -1/2 \frac{d}{dt} [N_2O_5] $$ ? The latter seems to be more apt, as the reaction rate must be -1/2 (disappearance rate of N2O5), which adheres to the stoichiometry of the...
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