Given the Information in the Table Above, Which of the Following Is the Experimental Rate Law?
Rate laws are mathematical equations that describe the relationship between the rate of a chemical reaction and the concentrations of its reactants. Determining the rate law is crucial for understanding the reaction mechanism and predicting the reaction rate under different conditions. In this article, we will analyze the data presented in a table and determine the experimental rate law.
The table provided presents the initial concentrations of reactants (A, B, and C) and the corresponding initial reaction rates for multiple experiments. To identify the experimental rate law, we need to compare the changes in concentrations of the reactants and their impact on the reaction rate.
Let’s consider the following overall reaction:
aA + bB + cC → Products
The experimental rate law is usually in the form:
Rate = k[A]^m[B]^n[C]^p,
where k is the rate constant and m, n, and p are the reaction orders with respect to A, B, and C, respectively.
To determine the reaction order with respect to each reactant, we will compare the reaction rates while keeping the concentration of each reactant constant and varying the concentration of one reactant at a time. By observing the change in the reaction rate, we can identify the order of each reactant.
Let’s analyze the data in the table:
Experiment 1:
– Concentration of A is doubled, while concentrations of B and C are constant.
– Reaction rate increases by a factor of 2.
– This suggests that the reaction is first-order with respect to A.
Experiment 2:
– Concentration of B is doubled, while concentrations of A and C are constant.
– Reaction rate remains constant.
– This suggests that the reaction is zero-order with respect to B.
Experiment 3:
– Concentration of C is doubled, while concentrations of A and B are constant.
– Reaction rate increases by a factor of 4.
– This suggests that the reaction is second-order with respect to C.
Based on these observations, we can conclude that the experimental rate law for this reaction is:
Rate = k[A]^1[B]^0[C]^2
= k[A][C]^2
This means that the reaction rate is directly proportional to the concentration of A and the square of the concentration of C, while the concentration of B does not affect the reaction rate.
FAQs:
Q: What is a rate law?
A: A rate law is a mathematical equation that describes the relationship between the rate of a chemical reaction and the concentrations of its reactants.
Q: Why is determining the rate law important?
A: Determining the rate law allows us to understand the reaction mechanism and predict the reaction rate under different conditions. It is crucial for studying and controlling chemical reactions.
Q: How do we determine the rate law experimentally?
A: The rate law can be determined by analyzing the changes in concentrations of reactants and their impact on the reaction rate. By comparing reaction rates while varying the concentration of one reactant at a time, we can identify the order of each reactant.
Q: What does the reaction order signify?
A: The reaction order represents the exponent to which the concentration of a reactant is raised in the rate law equation. It indicates how the concentration of a reactant affects the reaction rate.
Q: How does the rate constant (k) affect the reaction rate?
A: The rate constant determines the proportionality constant between the reactant concentrations and the reaction rate. It reflects the efficiency of the reaction and is influenced by various factors such as temperature, catalysts, and reaction conditions.
In conclusion, by analyzing the data provided in the table, we have determined that the experimental rate law for the given reaction is Rate = k[A][C]^2. This finding helps us understand the relationship between reactant concentrations and the reaction rate, providing valuable insights into the reaction mechanism.