New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Lecture 3: Rate Laws Continued (1/8)

by: it's lit notes

Lecture 3: Rate Laws Continued (1/8) Chem 31B

Marketplace > Stanford University > Chemistry > Chem 31B > Lecture 3 Rate Laws Continued 1 8
it's lit notes

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Notes from Lecture 3: Rate Laws Continued on January 8, 2016.
Principles of Chemistry II
Jennifer Poehlmann
Class Notes
Chemistry, Rate Laws, Rates, Reaction Rates, first order, second order, Rate Constant
25 ?




Popular in Principles of Chemistry II

Popular in Chemistry

This 3 page Class Notes was uploaded by it's lit notes on Saturday January 9, 2016. The Class Notes belongs to Chem 31B at Stanford University taught by Jennifer Poehlmann in Fall 2015. Since its upload, it has received 18 views. For similar materials see Principles of Chemistry II in Chemistry at Stanford University.

Similar to Chem 31B at Stanford

Popular in Chemistry


Reviews for Lecture 3: Rate Laws Continued (1/8)


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 01/09/16
  Friday  January 8, 2016  Important Information:  ­Pset #1 due Monday @ 2:30pm    Lecture 3: Rate Laws Continued  Clicker Question #1  You suspect that the reaction 2NO​ → 4NO​  + O​ is first order with respect toO​]. How  2​ 5​ 2​ 2​ 2​ 5​ should you plot [N2​ 5​versus time (t) to confirm your suspicion?  a.) [NO​] vs. t  2​ 5​ b.) [2​ 5​vs. 1/t  c.) ln[NO​] vs t  2​ 5​ d.) ln[2​ 5​vs. 1/t  e.) 1/[NO​] vs. t  2​ 5​ solution for a first order reaction, the equation2​ 5​= ­kt + ln2​ 50​ This equation is in  the form y = mx + b (the equation of a line), so in order to see if this reaction follows the trend,  you would plot y (ln[2​ 5​ vs. x (time).    Radioactive Decay  ● obeys first order kinetics and therefore the first order rate law  ● the general first order reaction rate can be applied to the rate of radioactive decay  ● rate = kN  ○ N = number of radioactive nuclei    Clicker Question #2  The radioactive element J has a half life of 3.5 years. How many years must pass before a  mole of J decays to 1/1000th of a mole?  a.) cannot be determined becaus1/2​ of a first­order reaction is independent of concentration  b.) 7.5 years  c.) 35 years  d.) 3500 years  e.) 38 years  solution t​ = 3.5 years     /[N]​ = 1/1000       t​ = 3.5 = .693/k → k = (.693/3.5)  1/2​ t​ 0​ 1/2​ ln ([Nt​[N0​ = ­kt  ln (1/1000) = ­(.693/3.5)t  t = 34.9 years ​5 years    Second Order Reactions  ● rate: ​rate = k[A]  ● differential rate law:­Δ[A]/Δ[t] = k[A]​2  ● integrated rate law:​1/[A]t​= 1/[A0​+ kt    Friday  January 8, 2016  ● half­life expression:​  t1/2​1/k[A]​ 0  ○ half life increases with time    Clicker Question #3  The following results were obtained for the reaction below at 25​ oC.  ­​ 2­​ 2­​ 2I (aq) + S​2​ 8​aq) → I​ 2​(aq) + 2SO​ 4​q)    Trial #  (I) M  (S​2​ 8​M  Initial Rate M/s  ­6 1  .080  .040  12.5 x 10​   2  .040  .040  6.25 x 10​­6  3  .080  .020  6.25 x 10​­6  ­6 4  .032  .040  5.00 x 10​   5  .060  .030  7.00 x 10​­6  a.) Which 2 trials should be chosen to find the order of the reaction with respect to S​ 2​ 8​​ a.) 1 and 2  b.) 2 and 3  c.) 2 and 5  d.) 1 and 3  e.) 1 and 5  solution: look for the trials where I​ is held constant because we are looking to see how the rate  2­​ depends on changing S​ 2​ 8​ncentration    b.) What are the units of the rate constant?  a.) M/s  b.) 1/(M x s)  2 c.) (M/s)​  d.) M​2/s  e.) 1/s  solution: looking at trials 1 and 3, we see that the concentration of S​ 2​ 8​d the rate of the  reaction are directly proportional, thus the order with respect to that reactant is 1. Looking at  trials 1 and 2, we can see that the rate of the reaction is also directly proportional to the  ­​ ­​ concentration of I​. Thus, the order with respect to I​ is also 1. Overall, the order of the reaction is  2, and the units for k for a 2nd order reaction are 1/(M x s).        Friday  January 8, 2016  Summary: Rate Laws  ● the reaction order (n) is experimentally determined and cannot be deduced from the net  reaction  ● molecules must collide before a reaction can occur between then  ● in an ​elementary step​ → the reaction order describes how many molecules must meet at  once  ● if the elementary step isA → products  ○ the reaction is first order because the coefficient of A is one  ○ no collisions are required  ● if the elementary step is​A → products  ○  the reaction is second order because the coefficient is 2  ○ 2 molecules must collide  ● rate­determining step­​  the slowest step is a reaction mechanism determines the overall  rate 


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Allison Fischer University of Alabama

"I signed up to be an Elite Notetaker with 2 of my sorority sisters this semester. We just posted our notes weekly and were each making over $600 per month. I LOVE StudySoup!"

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.