(b) The reaction 2 NO1g2 + Cl21g2¡2 NOCl1g2 is carried out in a closed vessel. If the partial pressure of NO is decreasing at the rate of 56 torr/min, what is the rate of change of the total pressure of the vessel?
Ch.14 - Chemical Kinetics
Chapter 14, Problem 27b
A reaction A + B¡C obeys the following rate law: Rate = k3B42. (b) What are the reaction orders for A and B? What is the overall reaction order?
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Identify the reaction order for each reactant from the rate law expression. The reaction order is the exponent of the concentration of each reactant in the rate law equation.
For reactant A, observe that it does not appear in the rate law expression. Therefore, the reaction order with respect to A is 0.
For reactant B, note the exponent of B in the rate law expression, which is 4. Thus, the reaction order with respect to B is 4.
Calculate the overall reaction order by summing the reaction orders of all reactants. In this case, add the reaction order of A and the reaction order of B.
The overall reaction order is the sum of the individual orders: 0 (order of A) + 4 (order of B) = 4.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Rate Law
A rate law expresses the relationship between the rate of a chemical reaction and the concentration of its reactants. It is typically formulated as Rate = k[A]^m[B]^n, where k is the rate constant, and m and n are the orders of the reaction with respect to reactants A and B, respectively. Understanding the rate law is essential for determining how changes in concentration affect the reaction rate.
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Rate Law Fundamentals
Reaction Order
The reaction order is the sum of the powers of the concentration terms in the rate law. It indicates how the rate of reaction is affected by the concentration of each reactant. For example, if the rate law is Rate = k[B]^2, the reaction is second order with respect to B, meaning that doubling the concentration of B will quadruple the reaction rate.
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Average Bond Order
Overall Reaction Order
The overall reaction order is the total of the individual orders of all reactants in the rate law. It provides insight into the complexity of the reaction mechanism. In the given rate law, if A has an order of 1 and B has an order of 2, the overall reaction order would be 1 + 2 = 3, indicating how the reaction rate responds to changes in concentrations of all reactants.
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Related Practice
Textbook Question
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Open Question
(b) The rate of decrease in N2H4 partial pressure in a closed reaction vessel from the reaction N2H4(g) + H2(g) → 2 NH3(g) is 74 torr per hour. What are the rates of change of NH3 partial pressure and total pressure in the vessel?
Textbook Question
A reaction A + B¡C obeys the following rate law: Rate = k3B42. (a) If [A] is doubled, how will the rate change? Will the rate constant change?
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Textbook Question
Consider a hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. (a) Write the rate law for the reaction.
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Textbook Question
Consider a hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. (e) By what factor does the rate change when the concentrations of all three reactants are tripled?
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Textbook Question
The decomposition reaction of N2O5 in carbon tetrachloride is 2 N2O5¡4 NO2 + O2. The rate law is first order in N2O5. At 64 C the rate constant is 4.82 * 10-3 s-1. (a) Write the rate law for the reaction.
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