CHEM102 Lecture Notes - Lecture 4: Reaction Rate, Reaction Rate Constant, Rate Equation

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olivesardine670

24 Sep 2017

School

University of Alberta

Department

Chemistry

Course

CHEM102

Professor

Sai Yiu

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CHEM102 Full Course Notes

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Plot of reactant concentration [a] against time for different order of reactions. Rate = k[a] s-1 ln[a]t = - kt + ln[a]o ln[a] vs time. If the rate constant is 7. 30 x 10-4 s-1, calculate the half- life of this reaction. The half-life of a first order reaction is given by: ln 2. Kt = - 7. 30 x 10-4 s-1 x 500. 0 s = - 0. 365. Percentage of h2o2 reacted = 100 - 69. 4 = 30. 6% A reaction is 50% complete in 30. 0 min. How long does it take to have the reaction 75 % complete if it is (a) a first order reaction and (b) a second order reaction? ln 2 (a) Half-life for first order reaction is given by: = 30. 0 min ln 2. For 75% complete, the fraction remaining is (100 75) / 100 = 0. 25. = 0. 25 = e 0. 0231 x t. = 60. 0 min ln 0. 25 = - 0. 0231 t ln 0. 25 t = -

Related Questions

Relating plots to the order of a reaction

Consider the following reaction:

Aâproducts

The plot of [A] versus t is linear for the zero-order reaction, the plot of ln[A]versus t is linear for the first-order reaction, and the plot of 1[A] versus t is linear for the second-order reaction. [A]represents the concentration of the reactant A.

Reaction order	Linear plot
zero	[A] vs. t
first	ln[A] vs. t
second	1[A] vs. t

The linearity of each graph can be used to identify the order of a reaction.

Characteristics of second-order reactions

For a second-order reaction, [A]âproducts, the rate of the reaction is given as rate= k[A]2, where k is the rate constant and [A] is the concentration of reactant A. The integrated rate law for second-order reactions is 1[A]t=kt+1[A]0, where [A]t is the concentration of reactant Aat time t, k is the rate constant, and [A]0 is the initial concentration of reactant A. This equation is of the type y=mx+b. Therefore, the plot of 1[A]tversus time is always a straight line with a slope k and a y intercept 1[A]0.

Consider the second-order reaction: 2HI(g)âH2(g)+I2(g) Use the simulation to find the initial concentration [HI]0 and the rate constant k for the reaction. What will be the concentration of HI after t = 7.05Ã1010 s ([HI]t) for a reaction starting under the condition in the simulation?

order inter. rate law graph slope

0 [A]=-kt+[A]_0 [A] vs t -k

1 ln[A]=-kt+ln[A]_0 ln[A] vs t-k

2 1/A=kt + 1/[A]_0 1/[A] vs t k

<?xml:namespace prefix = o ns ="urn:schemas-microsoft-com:office:office" /?> Using Integrated Rates Laws

The integrated rate laws for zero-,first-, and second-order reaction may be arranged such that theyresemble the equation for a straight line,.

A. The reactant concentration in a zero-order reaction was9.00