What would happen to Kc values in an experiment if the Beer's law constance (k) value used was low ( e.g you used 4000/M when the actual constant had a value of 5000/M)? Explain your answer
Absorbance = k*length cell*concentration
Cell length is constant.
You read an absorbance, so for any A read, plugging in k of 4000 instead of 5000 means the calculated concentration will be lower than it should be . What that does to Kc depends upon the Kc expression; i.e., the numerator and denominator (the number of terms and if any are raised to a power).
If the k value used in the experiment is lower than the actual constant, the calculated concentration of the solution will be lower than its actual value. This is because the absorbance values are directly related to the concentration of the solution through Beer's law.
Now, the Kc value is the equilibrium constant that represents the ratio of the concentrations of products to the concentrations of reactants raised to their respective stoichiometric coefficients in a balanced chemical equation. If the calculated concentration is lower than the actual concentration due to the lower k value used, the Kc value obtained in the experiment will be affected.
Depending on the Kc expression, specifically the stoichiometric coefficients and the number of terms involved, the deviation in Kc value may vary. If the stoichiometric coefficients are large or if there are multiple terms in the expression, the deviation in Kc value may be more significant.
Overall, using a lower k value in Beer's law would lead to an underestimation of the concentration values, which in turn would affect the calculated Kc value for the reaction. The extent of this deviation would depend on the specific Kc expression for the reaction being studied.
If the Kc expression involves the concentration of the substance being measured, then using a lower k value will result in a lower calculated concentration. This will, in turn, lead to a lower value for the equilibrium constant (Kc).
On the other hand, if the Kc expression does not involve the concentration of the substance being measured, then using a lower k value will have no effect on the equilibrium constant.
In summary, using a lower k value will generally result in a lower calculated concentration, which can impact the equilibrium constant value depending on the specific Kc expression.
To understand the effect of using a lower value for the Beer's law constant (k) on Kc values in an experiment, we need to consider that Kc is used to represent the equilibrium constant of a chemical reaction.
In the Beer-Lambert law equation, the absorbance (A) is given by A = k * l * c, where k is the Beer's law constant, l is the path length of the sample cell (which is constant), and c is the concentration of the solution being measured.
Since we are given that the actual value of k is 5000/M, but we used a value of 4000/M, it means our calculated absorbance (A) will be lower than it should be, as absorbance is directly proportional to k. This implies that the calculated concentration (c) will also be lower than it should be.
Now, the impact on Kc values depends on the specific expression for Kc in the equilibrium reaction. Kc is determined based on the concentrations of products and reactants at equilibrium. If the value of k used to calculate the concentration is lower than it should be, all the concentrations will be underestimated, resulting in a lower value for Kc than the actual value. This happens because Kc is calculated using the ratio of the concentrations of products to reactants, and altering those concentrations will affect the magnitude of Kc.
In summary, using a lower value for the Beer's law constant (k) in the Beer-Lambert law equation will lead to an underestimation of the concentration of the solution being measured. This, in turn, will result in a lower value for Kc in the equilibrium expression, as all concentrations are underestimated.