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

Chapter 15: Chemical Equilibrium Notes

by: Justin Sequerra

Chapter 15: Chemical Equilibrium Notes CHEM 1312

Marketplace > University of Texas at Dallas > Chemistry > CHEM 1312 > Chapter 15 Chemical Equilibrium Notes
Justin Sequerra
GPA 3.929
View Full Document for 0 Karma

View Full Document


Unlock These Notes for FREE

Enter your email below and we will instantly email you these Notes for General Chemistry II

(Limited time offer)

Unlock Notes

Already have a StudySoup account? Login here

Unlock FREE Class Notes

Enter your email below to receive General Chemistry II notes

Everyone needs better class notes. Enter your email and we will send you notes for this class for free.

Unlock FREE notes

About this Document

These notes will cover all that we have discussed about Chapter 15 (Chemical Equilibrium).
General Chemistry II
Dr. Sibert
Class Notes




Popular in General Chemistry II

Popular in Chemistry

This 8 page Class Notes was uploaded by Justin Sequerra on Friday February 12, 2016. The Class Notes belongs to CHEM 1312 at University of Texas at Dallas taught by Dr. Sibert in Winter 2016. Since its upload, it has received 190 views. For similar materials see General Chemistry II in Chemistry at University of Texas at Dallas.


Reviews for Chapter 15: Chemical Equilibrium Notes


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: 02/12/16
CHAPTER 15: CHEMICAL EQUILIBRIUM GENERAL CHEMISTRY II This general outline is meant as a supplement to the General Chemistry II (1312) course  taught at the University of Texas at Dallas and should not be taken as a standalone study  guide for the overall curriculum. However, I do hope that this broad summary of the textbook  helps you all in becoming successful undergraduate students here at UTD. ­ Justin Sequerra, “Chemistry is the study of matter. But I prefer to see it as the study of  change.” – Walter White, Breaking Bad 1 CHEMICAL EQUILIBRIUM 15.1 THE CONCEPT OF EQUILIBRIUM  Up until now, we have discussed chemical reactions as if they happen only once and have been completed after all the reactants have turned into the products.   However, that is not the case because chemical reactions do not proceed in that manner, since reactions can go BOTH WAYS. As soon as the reactants create enough products, the products start to go into the reverse reaction, whereby the products become the reactants and the reactants become the products. This back­and­forth transition between reactants and products continues until the system acquires a Chemical or Dynamic Equilibrium. The process hasn’t stopped however, since the reaction is still occurring and the  concentrations (of both products and reactants) have reached levels where they remain constant.  The rates of the reverse and the forward reactions are equal, where one is producing or consuming as much as the other.    (In reference to the figure): The reaction reaches equilibrium when the concentrations remain constant (when slope=0) and NOT at the point where the two concentrations are the same. 2 CHEMICAL EQUILIBRIUM 15.2 THE EQUILIBRIUM CONSTANT  Kc is constant at a constant temperature, so if the  temperature changes, the Kc changes. (I doubt there will be a question on the test asking you to find Kc at a  different temperature than the one given; if they do,  answer that you cannot perform the question since they  changed temperature, unless it deals with Le Chateliers  Principle).  Since K remains constant, changing the initial  concentrations will have NO EFFECT on it.  A large equilibrium constant (Kc>10^2) indicates that  the products will be favored at that equilibrium (the  concentration of products will be greater than that of the reactants). A small equilibrium constant (Kc<10^­2)  shows that the reactants are favored at equilibrium  (more concentration of reactants than products).   Unlike Kc, as the reaction proceeds, Qc will always  change since the concentrations of the species are also  changing as they try to come to equilibrium, or rather as they try to make Qc=Kc. Figure: This is the general form of the equilibrium  expression, however the units given are wrong (mol/L) 3 CHEMICAL EQUILIBRIUM 15.3 EQUILIBRIUM EXPRESSIONS  When all of the species in a chemical reaction are not in  the same phase, it is called a heterogeneous mixture, as  opposed to a homogeneous one.  Solids and liquids DO NOT appear in the equilibrium  expression for a heterogeneous reaction.  ­ We do not include these states because their relative concentrations do not change over the course of the  chemical reaction (if we double moles, we also  double volume).  When chemical equations that represent an equilibrium  are reversed, multiplied, combined with other equations, or any combination of the ones mentioned, the  corresponding changes must be made to the equilibrium constants. ­ This information is summarized below in the figure  Equilibrium expressions that contain only gases can be  written as Kc expressions or as Kp expressions. Kp  expressions have the same form as Kc expressions but   contain   partial p  rather than molar  concentrations. The same goes with Qc and Qk.  However, aqueous solutions can only be used in Kc  expression and NOT in Kp expressions.  Kc and Kp are not usually equal (as stated in the  4 sidebar). They are ONLY the same when the reaction  results in no net change in the number of moles of gas. CHEMICAL EQUILIBRIUM 15.5 CALCULATING EQUILIBRIUM CONCENTRATIONS  Starting concentrations can be used, along with the  equilibrium expression and equilibrium constant, to determine equilibrium concentrations  Steps for these kinds of questions: 1. Construct ICE tables (initial [ ], change, and  equilibrium  [ ]) and fill in any numbers given (even  zeros) 2. Calculate Q with the initial concentrations given so  you can see which direction the reaction will proceed  (compare to K, if Q>K=reactions goes left, and vice  versa) 3. Define x as the amount of a particular species (the one getting consumed by the reaction), and then use the  stoichiometric coefficients to define in terms of x the  amount of change the other species will undergo 4. Add the initial [ ]s and the change in [ ]s to get the  equilibrium concentrations. 5. Use the equilibrium constant and concentrations to  solve for x (use QUADRATIC EQUATION, but if you  find another way that is quicker (perfect square)USE  IT) 6. PLUG AND CHUG  ALWAYS MAKE SURE YOUR CHEMICAL EQUATIONS ARE  BALANCED!!!!!!!!  CHECK YOUR ANSWERS (if you have enough time 5 on the test)!!!! You can do this by plugging your calculated equilibrium concentrations into the equilibrium constant expression and compare the equilibrium constant you get (K) with the one given to you in the question. CHEMICAL EQUILIBRIUM 15.6 LE CHATELIER’S PRINCIPLE: FACTORS THAT AFFECT EQUILIBRIUM  The stresses that can be applied to a system at equilibrium include the addition or removal of a substance, changes in the volume of the reaction vessel, and changes in the temperature. ­ The summary of how the changes may affect the equilibrium is given in the figure below  “Shifting” to the right=more products will be produced  “Shifting” to the left=more reactants will be produced  Once the reaction once again achieves equilibrium  IT WILL HAVE THE SAME K AS BEFORE. The only thing that will change is the equilibrium positions ([ ]s) of the species involved in the reaction.  Changing the equilibrium position of a solid or a liquid will NOT affect equilibrium since it is not involved in the reaction  By adding an INERT GAS, the pressures will increase, but  6 since the volume remains constant, equilibrium is NOT  disturbed CHEMICAL EQUILIBRIUM 7 *PRACTICE PROBLEMS* 1. In an analysis of the following reaction at 100°C, the  equilibrium concentrations were found to be [Br2] = 2.3  × 10^−3 M, [Cl2] = 1.2 × 10^−2 M, and [BrCl] = 1.4 ×  10^−2 M. Write the equilibrium expression, and  calculate the equilibrium constant for this reaction at  100°C. 2. For the reaction, Kc is 2.3 × 10^−2 at 375°C. Calculate Kp for the  reaction at this temperature. 3. The following reactions have the indicated equilibrium  constants at a particular temperature: Determine the values of the equilibrium constants for  the following equations at the same temperature:  (a) ,  (b)  , and  (c)  . 4. Determine the equilibrium partial pressures of H2, I2,  and HI if we begin the experiment with 1.75 atm each of H2 and I2 at 430°C. 5. Indicate in which direction the following equilibrium will  shift in response to each change: a) Addition of XY 2s), b) Removal of Y (2), c) Decrease in container volume, d) Addition of X(s).


Buy Material

Are you sure you want to buy this material for

0 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."

Amaris Trozzo George Washington University

"I made $350 in just two days after posting my first study guide."

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."

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

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.