Chemical equilibrium summary

We've made it through 5 of the 8 chapters of Chem 102. Here is a summary of equilibrium, chapter15.

Next week we will start thermodynamics, Kevin will be in for demos on thusday for A04 and friday for A02.

Remember, midterm 2 on 13th March is approaching. If you still haven't gotten hold of a course pack yet it would be a good idea to get one.


Summary of chapter 15

We know chemical equilibrium has been reached when the concentrations no longer change with time
The equilibrium condition can be reached from either direction
The equilibrium constant of a reaction in the reverse direction is the inverse of the equilibrium constant of the reaction in the forward direction
The equilibrium constant of a reaction that has been multiplied by a number is the equilibrium constant of the reaction raised to a power equal to that number
The equilibrium constant for a net reaction made up of two or more steps is the product of the equilibrium constants for the individual steps
If K >> 1 (big) then equilibrium lies to the right (products)
If K << 1 (small) then equilibrium lies to the left (reactants)


Summary 2.
Leave solids and pure liquids out of equilibrium expressions, the concentration of these substances does not change with time.
Calculating Equilibrium Constants; is easy when we know all the equilibrium concentrations (or pressures), a balanced equation, and can write a rate expression. Don’t forget to convert to scientific notation.
When we know initial concentrations and an equilibrium concentration, use the stoichiometric coefficients to predict the change in concentrations.
Use the Initial, Change, Equilibrium (ICE) procedure to find all the equilibrium concentrations and sub these values into the equilibrium expression.


Comparing the magnitude of Q to Kc or Kp indicates the direction the reaction will shift to reach equilibrium


Calculating Equilibrium Concentrations; when we know K and all the initial concentrations only, use the ICE procedure and solve for x the change in concentration, possibly by solving a quadratic function.

Online quizzes 4-6 and midterm 2 announcement

The due date of on-line quizzes 4-6 is delayed until SATURDAY, March 7th at 11:59 pm.

The due date is Saturday, not Sunday. (this is to avoid time confusion as we change to daylight savings time at 2 am on Sunday morning)

The second midterm will cover chemistry of the troposphere (textbook, section 18.4), effects of acid rain, global warming and the greenhouse effect (pp. 14- 32 in course pack), liquids and phase diagrams (textbook, sections 11.3-11.6 inclusive), equilibrium (textbook, sections 15.1-15.6 inclusive) and intro to entropy up to and including the 3rd Law of Thermodynamics (textbook, sections 19.1-19.3, inclusive)

week 3

We've made it through the first 2 of 8 chapters of Chem 102.

Thermochemistry wrapped up with Hess's Law and Using Standard Enthalpies of Formation to calculate standard enthalpies of reaction.

I recommended a couple of problem sets from the textbook to compliment the notes. You will also find on the Chem 102 website, I'm sure you all have it bookmarked by now, that there is a new feature with a flashing arrow! entitiled animated problems. Here you'll find a few animated problem sets on gases and thermoschemistry...PLEASE CHECK THESE OUT.

Also as promised here are the couple of links from my sons new favourite TV show....destroyed in seconds.

http://ca.youtube.com/watch?v=45y1lSnlrH8

http://ca.youtube.com/watch?v=_KuGizBjDXo

This week we will continue our look at the Chemistry of the Environment. Kevin will be in to demonstrate Thermochemistry as well. Tuesday morning for the A02 group and wednesday afternoon for the A04 group. Its' thermochemistry so that means one thing to Kevin....Explosions!

Don't forget you can tackle at least 2 of the first 3 online quizzes and the 3rd one should be no problem with the course pack. Any questions related to the online quizzes should be directed to Dr Codding (contact details on the website), she will be able to help you.

Welcome to Chem 102, as we are 2 weeks in already it is time I updated the blog.

This is the spot where I post summaries of the material we have covered along with any links to websites and learning resources that I used in class.

This week we finished up Gases and began thermochemistry.

You should all be comfortable with the Gas Laws and be able to:
· Apply the ideal gas law to calculate the properties of gases under a variety of conditions, pressures, temperatures, volumes and amounts: PV=nRT
· Be able to convert pressures between different units
· Carry the units through equations and make sure you are using the correct gas constant
· Calculate the gas produced in chemical reactions and figureout how much reactant is required to give that much gas
· Collecting gases over water- factoring the water vapor pressure
· Calculate densities and Molar Masses of gases using the derived form of the ideal gas equation
· Describe the kinetic-molecular theory and explain the difference between real and ideal gases
· Under what conditions do real gases deviate most from ideal behavior (low temperature and high pressure).
· Be able to use the Van der Waals equation
· Remember to always check your answer- Does it seem right? If not check your units.

Here are a couple of links

You tube – collapsing can demo

http://www.youtube.com/watch?v=ZGhAeG13MTI&feature=related

Want to fill your tires with Nitrogen?

http://www.straightdope.com/columns/read/2694/is-it-better-to-fill-your-tires-with-nitrogen-instead-of-air

A site all about gases with demos and questions (I haven’t checked it all out so I’m not guaranteeing its quality!)

http://www.nclark.net/GasLaws

Remember to have a go at questions in the book, the best way to study for 102 is to do practice questions...Check out the learning commons schedule for help sessions. There are past exam questions at the back of your lab manual

http://web.uvic.ca/~chem102/learncom.html

Next up, thermochemistry

All about the transformation of energy in chemical reactions, in terms of heat and work!

Who’s doing the work ..the system or the surroundings?
Who’s gaining heat, who’s losing heat?
Remember to get signs correct

Well done to the eagle eye spotter who noticed the mistake on slide 7? And consequently in the book section 5.2, The second diagram: the system is gaining energy from the surroundings so E of system increases, not decreases as the diagram states.

Here are a couple of links

The unfortunate chemistry teacher under-estimating the potential energy sin bonds (acetylene)

http://www.youtube.com/watch?v=HUVNf-y349E&feature=related

The thermite reaction (Exothermic)

http://jchemed.chem.wisc.edu/JCESoft/CCA/samples/cca7thermite.html

If you have any questions feel free to send me an email, my contact information along with calendars etc is on my page
http://web.uvic.ca/~chem102/LEE/

I shall try and get the environment notes Chapter 18 on the page this weekend,
You should be able to do Online quiz 1 now. Don’t forget to do these quizzes they count for 9% of your final mark this time!