Class Blog 3/31/14

WELCOME BACK!!

TODAY’S NOTES 3/31/14

Le Chatelier’s Principle

Systems at equilibrium

-once something is at equilibrium you can nudge it to get it out of equilibrium

Does not like that

Textbook definition: --When a change/stress (in concentration, temperature, pressure, volume, addition of catalyst…) is applied to a system that is already at equilibrium, the position of equilibrium SHIFTS in a direction that tends to reduce the effect of that change

i.e.: -If a system is at equilibrium and you add reactants, it will shift to make more products until it reaches equilibrium again

i.e.: -If you add more heat, it will shift back to the place when it has less heat

3 Delta’s to think about:

1. Concentration

2. Pressure and volume

3. Temperature

1. Delta (change) in concentration

• When a reactant/product is added to a system that is at equilibrium, the system shifts away from the added component
• If a reactant or product is removed, the system shifts towards the removed component
• i.e. A(aq) + B(aq) → C(aq) + D(aq)
• add more A and the system shifts right to remove extra A

*Aqueous and gas rule applies

2. Delta (change) in pressure/volume

• Gas Laws:
• As volume goes down, pressure goes up (keeping temp constant)
• As volume goes up, pressure goes down (keeping temp constant)
• Systems that involve gases
• i.e.: 2A(g) + B(g) → 3C(g) + D(g)
• (3 moles reactants & 4 moles products)
• pressure increases, system shifts to the side with fewer molecules/moles of gas
• pressure decreases, system shifts to the side with more molecules

*Change of volume is “code” for change in pressure

3. Delta (change) in temperature

• Reminder: The value of k does change with temperature!
• Exothermic reaction: A(g) + B(g) → 3D(g) + heat
• As temp goes up, reaction shifts left (to try to get rid of extra heat energy)
• Endothermic: heat + A(g) + B(g) → 3D(g)
• As temp goes down, reaction shifts right

*Shifts away from thing that is making stress

Look at 4 HANDOUTS

-Intro to LeChatelier’s Principle

-LeChatelier’s Principle 1

-LeChatelier’s Principle 1 (cont)

-LeChatelier’s Principle 2

FINISHED 1st 2 worksheets in class (completed copies in notes folder)

HOMEWORK:

-Webassign due tomorrow at 11:59 pm

Finish worksheets:

-LeChatelier’s Principle 1 (cont)

-LeChatelier’s Principle 2

The next scribe: KATE MAKI

Wednesday March 19, 2014

What We Did Today:

Checked last night’s homework

Everyone gets two extra points on the last unit test because there was an error in the key.

Notes all put on Moodle

Today’s Handouts:

Unit test review* and Q calculation sheet**

*video and key posted

**can’t do unit packet questions 26 and 27 today because learning tomorrow

not enough space to do 26

Check hw

will be posted (hopefully)

went over equilibrium notes and reaction quotient notes (on moodle)

products divided by reactants raised to the power of their coefficients

hw: complete the two equilibrium constant worksheets from yesterday and one q worksheet

(total of three worksheets)

Today's Blog (3/18/14)

Tuesday, April 18. 2014!

Next Scribe: Elaine Sine

• First we checked in our graph homework. 
• Then we got back our old work (labs and worksheets).
• Then we checked over the equilibrium packet as a class.
• Then we took notes! :)

*** If equilibrium constant (K) is K > 1 then it favors the PRODUCTS, if K < 1 then it favors the REACTANTS

Today's Notes:

Chemical equilibria

(For a closed system)

Reactants ⇌ Products

• [] = means concentration (Moles/L)
• [Reactants] and [Products] never change once equilibrium is reached
• Looks like the reaction has stopped, but actually occurring simultaneously
• Closed sustems are at or apporaching equilibrium
• At equilibruim, the RATIO of [Reactants] to [Products] = constant

A⇌2B

The test is on Friday!

Joke of the day:

this one took me a while...

Homework: 3 worksheets passed out in the beginning of the class

Class Blog 3/17/14

We turned in our Alka Seltzer Lab and went over the Rate Reaction Packet. A key will be posted on Moodle.

We picked up 3 worksheets.

We divided into groups and did the Equilibrium Simulation Lab

Homework:
Graph class data from today's activity
The x-axis is Time
The y-axis is number of molecules: (atoms A/ Molecules A)

Divide the graph into two sections.

Tomorrow's blogger will be Elaine Sine 

March 14, 2014

MARCH 14, 2014

Alka-Seltzer Lab

Effect of Temperature on Reaction Rate:

Procedure: (1 example)

1. Constant: 1/2 of the film canister is filled with water (for every experiment's procedure!)

2.  First experiment was with room temperature water. Second procedure was with cold water. Third procedure was with hot water.

3. We measured the temperature of the water in the film canister.

4. We broke an alka-seltzer tablet in half and measured the mass. 

5. We put the measured alka-seltzert half and quickly put the alka-seltzer in the film canister, closed the film canister with the cap, and turned the film canister up-side down. 

4. Right when we flipped it we started timing (this all happens really fast, so while a partner is flipping we started timing)

5. Right when the flim popped, because of the pressure, we stopped the timer. We recorded the time in our data table. 

6. We did this for the rest if the water temperatures.

Data Table:

Temperature experiment:

Room temperature water:

Water temp: 25.9 degrees Celsius

Grams of half of one alka-seltzer tablet: 1.731 grams

Time it took to pop: 10.51 seconds

Cold water:

Temp of water: 4.6 degrees Celsius

Grams of 1/2 of alka-seltzer tablet: 1.783 grams

Time to pop: 22.10 seconds

Hot water:

Temp of water: 58.0 degrees Celsius

Grams of 1/2 alka-seltzer tablet: 1.457 grams

Time to pop: 3.05 seconds

Effect of Surface area:

*Room temperature water as constant*

*Water is still 1/2 of film canister*

Half of 1 aka-seltzer tablet: 1.384 grams

Temp of water: 25.4 degrees Celsius

Time it took to pop: 13.07 seconds

Two 1/4ths of alka-seltzer tablet: 1.495 grams

Temp of water: 25.1 degrees Celsius

Time it took to pop: 13.13 seconds

Crushed 1/2 alka-seltzer: 1.748 grams

Temp of water: 24.8 degrees Celsius

Time it took to pop: 5.71 seconds

Effect of Concentration:

*Room temperature water: as constant*

*Water filled up to1/2 of film canister*

1 alka-seltzer tablet: 3.234 grams

Water temperature: 24.1 degrees Celsius

Time to pop: 5.20 seconds

1/2 of an alka-seltzer tablet: 1.852 grams

Water temperature: 23.7 degrees Celsius

Time to pop: 12.68 seconds

1 1/2 alka-seltzer tablets: 5.153 grams

Water temperature: 23.7 degrees Celsius

Time it took to pop: 5.51 seconds

HOMEWORK:

Finish the lab worksheet! Due Moday!

Finish the Rate Expressions and Rate Constants packet! Due Monday!

WE DO NOT HAVE ANY WEBASSIGNS! :)

March 13, 2014

What we did today

1. Passed out the Reaction Rate investigation sheet

2. Started the Rate expressions and Rate constants Packet

To see what we did in the packet look on the moodle page for Rate expressions and rate constants packet

Important information for the Rate law

• When calculating the rate constant (k) you don't need to worry about the units
• When finding the rate of reaction do make sure your units are correct

Hw

1. Rate expressions and rate constants packet is due Monday

2. If you're going to be absent tomorrow make sure to check the blog for the data in lab due Monday

Class Blog 3-11-14

Class Blog 3-11-14

What we did in class:

• If you were confused on the Equilibrium Packet, don’t worry.
• The Key is posted on moodle.

• Mrs. Friedmann went over what our homework was for tonight (listed below)

• We took A LOT of notes covering 5 key topics:
• Collision Theory
• Reaction Mechanism
• Reaction Rate
• Energy and the Rate Determining Step
• Factors affecting the Reaction Rate

Homework:

• 3 Webassigns, due Wednesday @ 11:59pm
• Look at the key for the Equilibrium Packet and make corrections with a different color pen
• Take a look at the first part of the packet we got in class today titled: Rate Expressions and Rate Constants

Tomorrow's Blogger: Marlye Jerva

Hw: 3/10/14,

Hey guys,

Today we had a substitute, and essentially spent the whole period completing a packet titled, "Equilibrium".

This packet will be due tomorrow (3/11/14), along with 3 webassigns that will expire on wednesday.

Have a great day!

Tomorrow's blogger will be Melissa.

Blog - March 7, 2014

HOMEWORK: 2 Crash course videos posted in unit 9 moodle box - watch them and take notes on them, but take big picture notes. Summarize the point of each video, notes on the big idea.

http://www.youtube.com/watch?v=g5wNg_dKsYY&feature=youtu.be
http://www.youtube.com/watch?v=7qOFtL3VEBc

(The second link on Mrs. Friedman's page was broken for me, I think the second link on this blog is the video it was supposed to be.)

MRS. FRIEDMANN DEMONSTRATING EQUILIBRIUM:

CLASS ACTIVITY IN THE PIT: This was an equilibrium and balance activity in the pit using the 21 people in our class. Many situations were posed in which we were challenged to maintain equilibrium. Here were the patterns/requirements:

1) Maintain equilibrium. To achieve this, we lined people up as tall people on the ends of the people line, moving towards the shortest person in the class in the middle.

2) Maintain equilibrium and symmetry. To get this, we split the pit in two with one person in the middle and put 10 people on each side of the pit.

3) Maintain moving equilibrium and symmetry. Same as number 2 but the people were moving.

4) Maintain equilibrium and symmetry but people moved from side to side. To achieve this, we set up like number two but sent people from side to side. As one person went to one side, a different person went to the opposite side.

5) Maintain equilibrium and symmetry moving more than one person from side to side. We did the same as number four but sent two people from side to side.

6) Maintain equilibrium but not symmetry. To do this, we had people moving randomly on each side.

END OF CLASS DEMO (WITH FIRE): 

WEDNESDAY, MARCH 5, 2014

We got back:

-Specific Heat of Metal Lab report

-Heat of Combustion Lab report

-Thermochemistry quiz

-Woosh Bottle quiz

Quick notes:

-Higher specific heat capacity: harder to increase temperature (takes a lot of heat)

-A system can heat up or cool down without an enthalpy change

-Do not need to pay super attention to sig figs on test bc it is not what the unit is about

Went over last night’s hw: ...check moodle Unit 8 Keys folder

-More gas= super disordered= higher gas

-Endothermic= min enthalpy will be on reactants side

-Exothermic= min enthalpy will be on products side

-Minimum entropy and minimum enthalpy CAN be on the same sides

-Nature does NOT like to become more ordered

DeltaS tends to be positive in nature (in spontaneous processes)

-Calculate S= products MINUS reactants

-Positive= more order to less order

-Higher the S= more disorder

-S= "measure of messy"

-Entropy there ARE values for the elements

-kJ per Kelvin mole = entropy

-standard conditions = 25 degrees celsius and 298 kelvin

Homework:

-TEST TOMORROW

study session at 7 am

-Webassign due tonight by 11:59 pm

In class:
Turned in the lab

Notes:
Posted on Moodle
Enthalpy: Energy contained in chemical bonds

Hw:
2 webassigns due tonight
1 webassign due wednesday night
Entropy and Free Energy Worksheets