Calculating the Reaction Rates For the following reaction

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Calculating the Reaction Rates: For the following reaction: A(g) + B(g) → AB(g) The

Calculating the Reaction Rates: For the following reaction: A(g) + B(g) → AB(g) The reaction rate can be determined by measuring how fast the concentration of A or B decreases, or by how fast the concentration of AB increases. Change in concentration Ave. Reaction rate = Reaction time =

Example: During the reaction of carbon monoxide with nitrogen dioxide a total of 0.

Example: During the reaction of carbon monoxide with nitrogen dioxide a total of 0. 010 mol of nitrogen monoxide were formed (the volume of the container is 1. 00 L). Calculate the reaction rate. CO(g) + NO 2(g) → CO 2(g) + NO(g) Ave. Reaction rate = = Initial [NO] = 0. 00 M (mol/L) at t = 0. 00 s Final [NO] = 0. 010 M (mol/L) at t = 2. 00 s Ave. Reaction rate = = 0. 0050 M/s = 0. 0050 mol/(L. s)

Practice Problems: Use the data in the following table to calculate the average reaction

Practice Problems: Use the data in the following table to calculate the average reaction rates: Time (s) 0. 00 4. 00 Experimental data for H 2 + Cl 2 → 2 HCl [H 2] (M) [Cl 2] (M) [HCl] (M) 0. 030 0. 050 0. 000 0. 020 0. 040 0. 020 1. Calculate the average reaction rates: a) Expressed in moles H 2 consumed per liter per second. 0. 0025 mol/(L. s) b) Expressed in moles Cl 2 consumed per liter per second. 0. 0025 mol/(L. s) c) Expressed in moles HCl produced per liter per second. 0. 0050 mol/(L. s)

Reaction Rate Laws: The equation that expresses the mathematical relationship between the rate of

Reaction Rate Laws: The equation that expresses the mathematical relationship between the rate of a chemical reaction and the concentration of reactants is called a Rate Law. For example, for the reaction A → B the rate law is expressed as: Rate = k [A] k is the specific rate constant which depend on the temperature & is unique for each reaction. The k values are determined experimentally.

Rate = k [A] A large value of k means that A reacts rapidly

Rate = k [A] A large value of k means that A reacts rapidly to form B. Reaction Order: For a reactant defines how the rate is affected by the concentration of that reactant. For example in the equation above [A] means the same as [A]1. For reactant A the exponent 1 is called the reaction order. In other words, the reaction is the first order in A.

For a. A + b. B → products The general rate law for such

For a. A + b. B → products The general rate law for such reaction is: Rate = k [A]m [B]n m & n are the reaction orders for A & B respectively. The reaction is the m order in A and n order in B The overall order for the reaction is m + n. The overall reaction order of a chemical reaction is the sum of the orders for the individual reactants in the rate law.

Example: 2 NO(g) + 2 H 2(g) → N 2(g) + 2 H 2

Example: 2 NO(g) + 2 H 2(g) → N 2(g) + 2 H 2 O(g) The rate law, determined experimentally is: Rate= k [NO]2 [H 2] The reaction is described as second order in NO, first order in H 2 and third order overall. The rate depend on the concentration of the reactants as follows: If [NO] doubles the rate quadruples. If [H 2] doubles the rate doubles

Independent work (pages 604 -608): 1) 2) 3) 4) Draw the graph & answer

Independent work (pages 604 -608): 1) 2) 3) 4) Draw the graph & answer a), b) & c) p. 605. Copy Sample-Problem 18. 1 p. 606. Draw the graph & answer a), b) & c) p. 607. Copy the two steps for the mechanism of the reaction show (p. 608) & summarize the paragraph bellow it. 5) Exercises 9, 10, 11, 12, 13, 14, 15 & 16 p. 608.

Determining Reactions Order: (Glencoe p. 544)

Determining Reactions Order: (Glencoe p. 544)