DOC PREVIEW
UI CHEM 1120 - Reaction Rates, Concentration and Average vs Instantaneous Rates
Type Lecture Note
Pages 7

This preview shows page 1-2 out of 7 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 7 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 7 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 7 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

CHEM 1120 1st Edition Lecture 5Outline of Last Lecture I. Colligative Properties of Electrolyte SolutionsA. van’t Hoff Factor II. ColloidsA. Definitions and typesB. Hydrophillic vs Hydrophobic ColloidsOutline of Current Lecture I. Reaction RatesII. Concentration and RateIII. Average Rate vs Instantaneous RateA. Definitions, ExamplesB. Reaction Order and Units of Rate Constants Current LectureI. Some reactions, like rust building up on an old car, take a long time to occur and are very slow. Some reactions, like an explosion, take a shorttime to occur and are very fast. Other reactions, like cooking eggs, are in between fast and slow. I know you are probably wondering why we care, and the answer is because sometimes we want to manipulate thereactions’ speed and maybe make our cars rust way slower than normal, or maybe we want to make cement solidify a lot faster than normal. Or maybe you want to slow down cancer? Ozone depletion? Before we look at factors affecting the speed, we must look at reaction rates mathematically. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Example:Which expression correctly states the rate of the reaction? N2 (g) + 3H2 —————> 2NH3 (g)Solution: rate = + Δ[NH3] / 2 ΔTII. The rate or speed of a reaction usually depends on the concentration… In most cases for a generic reaction, aA + bB ——> cC + dD,*The rate law looks like: Rate = k [A]m[B]nk = rate constant (depends on the temperature)m = order of reaction with respect to An = order of reaction with respect to Bm + n = order of overall reactionm and n are usually integersm and n do not need to be equal to a and bFour factors affect the speed of a reaction: 1. Reactant physical state (ex: fine powder/solid block)2. Reactant concentration (ex: dilute acid/concentrated acid)3. Temperature (ex: boiling an egg)4. Catalysts (automobile catalytic converter)III. When talking abut average rate vs instantaneous rate, many tend to get confused because they do not understand the difference between the words average and instantaneous. To illustrate these differences better, an exampleis helpful. When you drive to New York, you can take the total number of miles and divide by the time it took you to get there for the average traveling speed. You can also read the speedometer’s number for your instantaneous speed at which you are traveling that moment. The same dealcan be applied to the speed of chemical reactions.Average Rate = the rate of reaction averaged over a period of timeExercise: Compute the average rate of the previous reaction for the first 10 seconds of the reaction.Instantaneous Rate = the rate of reaction at a particular point in timeExercise: Compute the instantaneous rate of the previous reaction 15 seconds into the reaction.Here is an example of reaction order:The reaction above is 1st order with respect to O3, 1st order with respect to NO2, and 2nd order overall (1st + 1st = 2nd overall).The reaction above is 2nd order with respect to NO2, and 2nd order overall.The third and final reaction above is 1st order with respect to (CH3)3CCl, 0 order with respect to water, and 1st order overall.Units of rate = (units of rate constant)(units of


View Full Document

UI CHEM 1120 - Reaction Rates, Concentration and Average vs Instantaneous Rates

Type: Lecture Note
Pages: 7
Documents in this Course
Load more
Download Reaction Rates, Concentration and Average vs Instantaneous Rates
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Reaction Rates, Concentration and Average vs Instantaneous Rates and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Reaction Rates, Concentration and Average vs Instantaneous Rates 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?