When experimentally determining the rate law, i am getting a negative fraction. is that right or am i doing something wrong?
It is possibly right. I'd have to see you calculations to determine that. It would mean that the reaction is proceeding backwards.
To experimentally determine the rate law of a chemical reaction, you typically measure the initial rates of the reaction under different conditions, such as varying the concentrations of reactants. Then, based on the collected data, you can determine the order of reaction with respect to each reactant and the overall rate constant.
In most cases, the rate law is expressed as a power law equation, such as rate = k[A]^m[B]^n, where [A] and [B] represent the concentrations of reactants, and m and n are the respective order of reaction for each reactant. The rate constant, k, is a proportionality constant that relates the rate of the reaction to the concentrations of the reactants.
Now, if you find that one of the calculated orders or the rate constant is a negative fraction, it could indicate that the reaction is proceeding in the reverse direction. This means that the reactants are actually being formed from the products or that the reverse reaction is occurring faster than the forward reaction.
To confirm this, it would be helpful to double-check your experimental data, calculations, and any assumptions made during the determination of the rate law. Additionally, consider conducting additional experiments to gather more data points and ensure the accuracy of your results.
In summary, a negative fraction in your rate law calculations suggests the possibility of a reverse reaction. Double-check your data and calculations to ensure accuracy and consider conducting additional experiments to confirm your findings.