Ch.13 - Chemical KineticsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
General Rate

Concept #1: Understanding Average or General Rate. 

Transcript

Hey guys! In this brand new video, we're going to take a look at general rate. We've been talking about chemical kinetics this whole time. We said kinetics is just looking at the rate or speed of a chemical reaction. We're going to say general rate is the simplest way to help us explain what exactly rate is. We're going to say general rate is just looking at the change in the amount of a compound whether it’d be a product or reactant over time.
Generally, this amount is in concentration which means molarity. Here we're going to say rate equals delta A, remember delta just means change so the change in A over the change in time. What exactly does A mean? We said it already. A equals reactants or products. We're going to say this semester, the use of brackets, brackets fundamentally mean concentration. What exactly does concentration mean? Concentration means molarity.
Just in case you don't know what molarity is, remember molarity is the moles of solute over liters of solution. If you see brackets around something, it means the concentration of that compound whether it’d be a product or a reactant. Remember, solute is the smaller portion that gets dissolved inside of our solvent. The liquid itself that's doing the dissolving is the solvent. The smaller portion is the solute. Solute plus solvent equals solution.

General or Average Rate is the change in the concentration of a compound over a period of time.

Example #1: The following equation shows the production of NO and H2O by oxidation of ammonia. 

4 NH3 (g) +  5 O2 (g)   →  4 NO (g)  + 6 H2O (l)             

a. What is the average rate of each compound in the balanced equation? 

Example #2: b) What is the rate of NH3 in the reaction between 2 and 6 minutes at 40oC? 

Example #3: c) Determine the instantaneous rate of the following reaction.

Stoichiometric Rate

In a stoichiometry based question we are accustomed to doing a mole-to-mole comparison. Now in Chemical Kinetics, we will do instead a rate-to-rate comparison. 

Example #4: The decomposition of dinitrogen pentoxide is described by the chemical equation:

2 N2O5 (g)   --->  4 NO2 (g)  +  O2 (g)

If the rate of disappearance or decomposition of O2 is equal to 2.20 M/min at a particular moment, what is the rate of appearance or formation of N2O5 at that moment? 

Practice: The formation of alumina, Al2O3, can be illustrated by the reaction below: 4 Al (s) + 3 O2 (g) ----> 2 Al2O3 (s). At 750 K it takes 267 seconds for the initial concentration of Al2O3 to increase from 6.18 E-5 M to 5.11 E-4 M. What is the rate of Al?