Determination Of The Following Equation For The First Order Reaction
The graph for run 1, which plotted ln(Abs at 595nm) versus time, a first order reaction, with an R^2 value of 0.99621 was the most linear. Therefore, crystal violet is a first order reaction. The observed rate constant from run 2, as shown in figure 4, was significantly lower then the observed rate constant from run 1, shown in figure 1. Therefore, the R^2 for the first order reaction for run 2, 0.946418, represented in figure 4, which is also extremely low, was not taken into consideration for calculations and observations due to the lack of linearity.
On the other hand, the order in respect to 〖[OH〗^-] would have been found by using the observed rate constants, which are the negated slope values for the plots ln(abs at 595nm) versus time. As stated, since the data recorded from run 2 is not reliable, the observed rate constant was not used for calculations. Therefore, the accepted value of ‘one’ was assumed, making the order with respect to OH^- one. With the order of both crystal violet and hydroxide found to be first order, with an overall reaction order of two, the rate law for the reaction of crystal violet with hydroxide is found to be equation 9, Rate=k[C〖V]〗^1 …show more content…
[〖NaOH]〗^1.
k_obs differs from the numerical value of k in the sense that k_obs changes depending on the constant concentration of hydroxide.
The true rate constant for the overall reaction, k, does not depend on hydroxide’s concentration and will remain constant regardless of the concentration. On the contrary, the rate constant is dependent on temperature; therefore, the temperature must be kept the same throughout the experiment. The observed rate constant and true rate constant had units of s^(-1) and M^(-1) s^(-1), respectively. The units for both the observed rate constant and true rate constant were found with the use of equation 8 and 9. (With the knowledge obtained that crystal violet is a first order reaction and the accepted value of “one” for y, making hydroxide a first order reaction, as
well.)
The true k value directly relates to temperature and errors could be due to a temperature decrease. More errors could include not being able to insert the cuvette into the spectrometer quick enough, failure to properly clean the cuvettes and mix the sodium hydroxide and crystal violet, and failure to properly handle solutions. All of these errors could have played a role in the inaccurate data collected from run 2, resulting in the extremely low r^2 value of 0.946418. By repeating the experiment more times, keeping the temperature constant, and cleaning the cuvettes better could improve further data collected and results of further runs
On the other hand, the order in respect to 〖[OH〗^-] would have been found by using the observed rate constants, which are the negated slope values for the plots ln(abs at 595nm) versus time. As stated, since the data recorded from run 2 is not reliable, the observed rate constant was not used for calculations. Therefore, the accepted value of ‘one’ was assumed, making the order with respect to OH^- one. With the order of both crystal violet and hydroxide found to be first order, with an overall reaction order of two, the rate law for the reaction of crystal violet with hydroxide is found to be equation 9, Rate=k[C〖V]〗^1 …show more content…
[〖NaOH]〗^1.
k_obs differs from the numerical value of k in the sense that k_obs changes depending on the constant concentration of hydroxide.
The true rate constant for the overall reaction, k, does not depend on hydroxide’s concentration and will remain constant regardless of the concentration. On the contrary, the rate constant is dependent on temperature; therefore, the temperature must be kept the same throughout the experiment. The observed rate constant and true rate constant had units of s^(-1) and M^(-1) s^(-1), respectively. The units for both the observed rate constant and true rate constant were found with the use of equation 8 and 9. (With the knowledge obtained that crystal violet is a first order reaction and the accepted value of “one” for y, making hydroxide a first order reaction, as
well.)
The true k value directly relates to temperature and errors could be due to a temperature decrease. More errors could include not being able to insert the cuvette into the spectrometer quick enough, failure to properly clean the cuvettes and mix the sodium hydroxide and crystal violet, and failure to properly handle solutions. All of these errors could have played a role in the inaccurate data collected from run 2, resulting in the extremely low r^2 value of 0.946418. By repeating the experiment more times, keeping the temperature constant, and cleaning the cuvettes better could improve further data collected and results of further runs