Download presentation

Presentation is loading. Please wait.

1
**KINETICS -REACTION RATES**

AP Chem

2
**RATE Dquantity / Dtime mol / L• s**

Average rate of product produced = negative average rate of reactant consumed Rate of a Rxn is always Positive Reaction rates are determined experimentally by measuring concentrations at various times

3
Rate Laws Equation that expresses the mathematical relationship between the rate of a rxn and the concentration of reactants Include the specific rate constant “k” k = numerical value that relates rxn rate & concentration of reactants at a given temp

4
**Specific Rate Constant (k)**

k is unique for every rxn k will NOT change with concentration k will change with temperature A large k value means that the reactants rapidly form products Units can vary depending on situation ie: L/mol•s, L2/mol2•s, 1/s

5
**General Form of Rate Laws**

General Reaction: aA + bB products General Rate Law: Rate = k [A]m[B]n (m & n = reactions orders for A and B) Reaction Order defines how the rxn rate is affected by concentration of reactants

6
**Determining Reaction Order by Method of Initial Rates**

Example:

7
**Integrated Rate Laws Shows how concentration depends on time**

Used for aA products Three types of Integrated Rate Laws: Zero Order First Order Second Order

8
**Zero Order [A]t = -kt + [A]0 t1/2 = [A]0 / 2k**

[A]0 = initial concentration [A]t = concentration at time t Half life – time required to reach half of original concentration t1/2 = [A]0 / 2k

9
**First Order ln[A]t = -kt + ln[A]0 ln[A]t – ln[A]0 = -kt**

ln([A]t/[A]0) = -kt t1/2 = 0.693/k

10
Second Order 1/[A]t = kt + 1/[A]0 1/[A]t – 1/[A]0 = kt t1/2 = 1/k[A]0

11
**Determining Integrated Rate Law Order Graphically**

You can determine the rxn order if given [A] and time by making a graph. Plot: [A] vs. time ln[A] vs. time 1/[A] vs. time (see which graph is linear)

12
**Zero Order rate is constant; doesn’t change with concentration**

plot of [A] vs. time = linear Rate=k -k=slope

13
**First Order Concentration and rate are directly proportional**

Plot of ln[A] vs. time = linear Rate = k[A] -k=slope

14
**Second Order If [reactants] doubles, rate quadruples**

Plot of 1/[A] vs. time = linear Rate = k[A]2 k=slope

Similar presentations

Presentation is loading. Please wait....

OK

Chemistry 40S Unit 3: Chemical Kinetics Lesson 4.

Chemistry 40S Unit 3: Chemical Kinetics Lesson 4.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on shell scripting language Ppt on online banking project in java Ppt on acid rain Ppt on series and parallel circuits lessons Ppt on water scarcity in california Evs ppt on pollution Store design and display ppt on tv Ppt on cse related topics to accounting Ppt on our government of india Ppt on data collection methods in research