Integrated Rate Law Integrated Rate Law A reaction

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Integrated Rate Law

Integrated Rate Law

Integrated Rate Law: A reaction is followed for an extended period of time. Method

Integrated Rate Law: A reaction is followed for an extended period of time. Method of Initial Rates A reaction is followed for only the first few moments of the reaction.

Advantages of the Method of Initial Rate: 1. Useful when a reaction is reversible.

Advantages of the Method of Initial Rate: 1. Useful when a reaction is reversible. The reverse reaction won’t significantly contribute to the first few moments of the reaction. 2. Useful for very fast or very slow reactions.

Advantages of the Integrated Rate Method: 1. Useful for moderate length reaction. 2. Doesn’t

Advantages of the Integrated Rate Method: 1. Useful for moderate length reaction. 2. Doesn’t require multiple experiments to determine the order of the reaction.

Common Uses of the Method of Initial Rates: 1. To determine the order of

Common Uses of the Method of Initial Rates: 1. To determine the order of the reaction. 2. Find the rate constant, k.

Common Uses of the Method of Integrated Rate Laws: 1. To determine the order

Common Uses of the Method of Integrated Rate Laws: 1. To determine the order of the reaction. 2. Find the rate constant, k. 3. To determine the concentration at a certain time. 4. To determine at what time a certain concentration will be reached.

Concentration of D over Time This is the raw data collected during the experiment

Concentration of D over Time This is the raw data collected during the experiment Start your analysis by graphing [D] v. Time

R 2= 0. 9737 The data do not form a straight line. The R

R 2= 0. 9737 The data do not form a straight line. The R 2 value only has one “ 9”. This reaction is NOT zero order!

Next, convert your raw data to natural logs and graph ln[D] v. time

Next, convert your raw data to natural logs and graph ln[D] v. time

R 2 = 1. 0 The data DO form a straight line. The R

R 2 = 1. 0 The data DO form a straight line. The R 2 value is 1. 0. This reaction is first order.

Normally, when you get a straight line you stop making graphs. For teaching purposes,

Normally, when you get a straight line you stop making graphs. For teaching purposes, let’s go ahead and look at the third kind of graph: 1/[D] v. time