Select Page

## Q3 : Week 9 – 4/1 – 4/5

#### Refresh this page every time you arrive!  I update this daily!!!

If you have not already please join the REMIND for this class.

– Regarding Homework assignments – IF you cannot complete the assigned homework before school the next day you must email me otherwise all late assignments will now be zeros.  No late work be accepted UNLESS I GET AN EMAIL!!!

Please Make sure Your read all instructions for all assignments.

Make Sure Powerschool grades are accurate!!

________________________________________________________                                                                                                                   4/1 – Monday – A DayMini Spring Break

____________________________________________________________________                                     Jump to: Tuesday Homeworktop         4/2 – Tuesday – A Day – 2/3a Lab, 4

Main focus –

a) To complete the equilibrium Lab – Lab 26

b) To answer equilibrium FRQ problems that deal with gases and partial pressures

c) To Begin the Concepts Rate Law

Period 2,3a:

1.  Complete Lab – 26 with added last page.
– Write objectives, complete last page
– Use demonstration to identify whether reaction is exothermic or endothermic

2.  Complete Classwork Frq Equlibrium selected problems:

3.  Rate Law begins

Period 4:

1. & 2. above.

_______________________________________________________________________________

Lab 26 – The Determination of Keq for FeSCN2+

Lab 26 – Equilibrium of FeSCN.pdf

Objectives:

1. To use spectrophotometry to measure the concentration of the complex ion.
2. To use the dilution formula to determine the concentration of the reactants.
3. To use an ice table to determine the concentrations of the reactants at equilibrium.
4.  To calculate the Keq of the reaction using equilibrium expression.

The reaction with a very low Keq and a △G that is not too highly positive or negative is reversible and can contain reach a equilibrium.  The following reaction is one that contains a complex ion that utilizes crytal field theory to provide the color.

Fe+3 (aq)  +  SCN (aq)  ⇔ FeSCN2+
pale yellow                                                                blood red

We set the spectrophotometer to measure the absorbance at 450 nm because that is the peak absorbance of the blood red complex ion, FeSCN2+:

*A sample of the FeSCN2+ in one our spectrophotometers.

We will use the spectrophotometer measure the amount of the products (blood red color) when different concentrations of the reactants reach equilibrium. Knowing the concentration of the product at equilibrium that we get from measuring the absorbance we can determine the amount of  reactants at equilibrium. From these values and the equilibrium expression we can calculate the Keq value for room temperature.

Fe+3 (aq)  +  SCN (aq)  ⇔ FeSCN2+

I:          starting [  ]                starting [  ]                            0

C:              – X                                  -X                                   + X

E:        starting [  ]  – X         starting [  ] – X                         X

↑                                                                                                                    Absorbance –> [   ]

_______________________                                                                                                                                                                                                                           TODAY’s NOTES:

a) You are to read my notes on RATE LAW that is posted in the 3rd quarter:

http://mrgrodskichemistry.com/rate-law-notes/

*You are to read my notes up to and including skill 5 and skill 7!
Complete RATE LAW Skills from the NOTES:
Skill #1 – Identify the orders of the reaction from the experimental evidence – Eyeball method
Skill #2 – Determining catalysts and intermediates in mechanisms
Skill #3 – Determining Rate Law from mechanisms or evaluating the best mechanism
Skill #4 – Determine the rate law constant with correct Units
Skill #5 – Calculate the Rate for the initial concentrations that are not in the experiment.
Skill #7 – Determine the Orders by math (when the eyeball method can’t be used.) – NON-EYEBALL METHOD!

I have worked really hard to write a complete chapter in RATE Law that I hopefully is clear and logical and breaks down every skill you need to learn.
RATE LAW looks daunting at first but trust me everyone loves rate law once you let it sink in.  PLEASE do this before you view todays class lectures.  The Lectures will make MUCH more sense.
b) Rate Law Lecture 1 is what I did today, keeping in mind what you read in the Rate Law Notes.

Rate Law Intro Lecture 1:

Rate Law Intro Lecture 2:

4/2 – Tuesday’s Homework: –

*The Classwork (Equilibrium FRQ Examples ) that was started in class does NOT
have to be completed for HW.

1. View the Rate Law 1 Intro lecture above

2. Follow along with me in completing the RATE LAW RUMBLE worksheet with the
Rate Law Intro Lecture 2 above.
You really need to view the first lecture to understand these questions.

This Question contains: RATE LAW SKILLs (in your notes) :  #1, #2, #3, #4, #5, #7

Rate Law Rumble 1819.pdf

Rate Law Rumble key .pdf

___________________________________________________________________________              Jump to: Wednesday Homework / top 4/3 – Wednesday – B Day – 2, 3b/4 Lab

Main focus –

a) To introduce Rate Law
b) To determine the order of a reaction through experimental evidence AND                                determine the best mechanism for an overall reaction.

c) To Calculate the orders of reaction (when eye ball method does not work                            d) To use stoichiometry in Rate Law questiions                                                                                  e) To determine the Rate Law through Fast Equilibrium problems.

Period 2:

LAST NEW TOPIC: Rate Law – path function from Reactants to Products

1. Intro to Rate Law – Last New topic! We are very close to being done with the entire course!

a) effective collisions  – collision theory

b)  factors that effect RATE (speed) of reactions (increase the frequency of effective collisions)

i) RATE Law deals with the initial rate of a (spontaneous) reaction BASED on the amount of concentration

Rate Law does not measure spontaneity and spontaneity does not measure Rate Law!

c) Determine the Rate Law based experimental evidence

i) eyeball method vs calculating

d) rate Law predicts the best mechanism by predicting the elementary step that is rate determining.

The slowest step in a mechanism is Rate Determining Step (RDS) !

i) Coefficients = exponents ONLY for single step reactions = elementary reactions = single step reactions

Coefficients becomes orders for Reactants in the RATE LAW EQUATION for ELEMENTARY REACTION ONLY !

ii) Catalysts vs Intermediates.

iii) Determining the mechanism ( a group of elementary steps that overall = the overall reaction) that best represents                          the experimentally determined RATE Law.

Kinetics 1 Rate Law .pdf

Kinetics 1 – Rate Law Key.pdf

Period 3b/4:

1. Complete Lab 26 by calculating the absorptivity constant for the test solutions                                                Collect!

2. Intro to rate law – same as above

Rate Law Presentation:

Liquid Oxygen and the Popsicle Stick – Rate increases with increased CONCENTRATION of oxygen

Light sticks and Temperature – Rate increases with increase in TEMPERATURE.

Surface Area of saw dust- Rate increases with increase in SURFACE AREA.

_______________________                                                                                                                                                                                                                         TODAY’s NOTES:

RATE orders –

R = [x]0  =   zero order    =    no effect on the rate of a reaction

R = [x]1   =   1st order       =    Rate changes exactly as the [x] changes

R = [x]2  =    2nd order     =    Rate change is the square of the [x] change

R = [x]3  =    3rd order      =    Rate change is the cube of the [x] change

R = [x]1/2 =  1/2 order       =    Rate change is the square root of the [x] change

R = [x]-1  =  -1 order         =     Rate change is the inverse of the [x] change

Complete RATE LAW Skills from the NOTES:  http://mrgrodskichemistry.com/rate-law-notes/
Skill #1 – Identify the orders of the reaction from the experimental evidence – Eyeball method
Skill #2 – Determining catalysts and intermediates in mechanisms
Skill #3 – Determining Rate Law from mechanisms or evaluating the best mechanism
Skill #4 – Determine the rate law constant with correct Units
Skill #5 – Calculate the Rate for the initial concentrations that are not in the experiment.
Skill #6 – Determine the Stoichiometric loss of reactants to gain of products
Skill #7 – Solve for the Rate Law orders without EYEBALL method
Skill #8 – Solve for the Rate Law orders with Graphs
Skill #9 – Solve for time, concentration, or using integrated Rate Law formulas

Worksheets worked on so far.

Rate Law Rumble 1819.pdf

RATE LAW SKILLs (in your notes) :  #1, #2, #3, #4, #5, #7

Kinetics 2 – rate law.pdf – (1984B, 1991B)

RATE LAW SKILLs (in your notes) :  #1, #4, #7

Rate Laws from Mechanisms (Optional) Lecture:

3: Fast Equilibrium Lecture:

_____________________________________________________.                                                                                         jump to:  top   4/3 – Wednesday Homework:

1.   Please view the Fast Equilibrium Lecture ABOVE and follow along with me following worksheet.

Kinetics mechanisms – fast equilibrium.pdf

Kinetics mechanisms – fast equilibrium KEY.pdf

2. Please complete the first 2 pages of the Kinetics 2 worksheet  (1984B, 1991B) and review with the key.             (ALL Classes)

*If you can use the eyeball method to determine the Rate Law then do so!!!!!

SKIP question C of 1984B

This question contains: RATE LAW SKILLs (in your notes) :  #1, #4#7

You might (period 3/4 saw this but not period 2) NEED ME to show you how calculate the orders from the experiment (IF THE EYEBALL METHOD – (SKILL 1) will not work)
Please view the NON- EYEBALL METHOD (SKILL 7) video below:

RATE LAW SKILLs (in your notes) :  #1, #4, #7

Kinetics 2 – rate law.pdf

Kinetics 2 – rate law KEYp .pdf

NON-EYEBALL Method of getting the order of reaction: SKILL 7 in the notes

________________________________________________________________________                               Jump to: Thursday Homework / top  4/4 – Thursday – A Day – 2/3a Lab, 4

Main focus –

a) To Review Rate Law Determination from experimental evidence and/or mechanisms

b) To determine the Rate law from a fast equilibrium step in a mechanism.                          c) To verify the correct mechanism for rate determined from experimental evidence.        d) To model how to solve for the non-eyeball method of calculating the reaction orders.

Period 2,3a:

1. Review of orders determined through RATE experiments:

a) help us build an equation that will measure initial rate or instantaneous rates of reactions

b) Help us understand how a reaction occurs either by a single step or a multiple step process = mechanism

2.  Review the Fast Equilibrium elementary step that helps determine the Rate Law formula for the overall reaction.

3. Review of Rate Law Rumble worksheet.

4. Review the homework problems – appropriate mechanisms for Rate Laws –

Kinetics 2 – rate law KEYp .pdf

also skill #6 – stoichiometry in rate law

5. When you need to go beyond the eyeball method – Calculating the orders.

* Eyeball method vs. Mathematical method (NON-EYEBALL Method) of finding the orders –skill #7

6.  RATE LAW TEST

Period 4:

1 – 5 above.

__________________________________________________                                                                                 jump to:  top                       4/4 – Thursday Homework: –

Integrated Rate Law Formulas:
Please follow these instructions. If you do these out of order you will not learn an reinforce the concepts that I want you to review.

1. Please watch the Integrated rate law derivation lesson below on the derivation of the 0th, 1st, and 2nd Order Integrated  Rate Law formula.

These formulas help us utilize time with changes in our reactant concentrations!
These formulas are integrated formulas (Calculus) and they are needed to link “real time” with actual concentrations (area under curve).  Remember that Rate Law is the Rate from INITIAL CONCENTRATIONS of reactants. That Rate that we have been calculating for changes the instant the chemical reaction starts so it really becomes useless AFTER some time period after time zero.  They utilize concepts of derivative and integrals which many of you have NOT had in math YET! You do not need to use these concepts to answer the following questions, just the formulas:

How long does it take for the reaction to be completed?
How long does it take for the concentration of my reactant to reach a certain value?
Given the time, how much of the reactant remains?
What is the shelf life of the chemical? (how long does it take to decompose?)

2.  Read the notes on the new INTEGRATED RATE LAW Formulas – Skill 8 and Skill 9

3. Complete the following worksheet and review with the keys OR THE VIDEO POSTED BELOW:

2005B 2009 Kinetics quiz 2013 with college board and grodski keys.pdf

These formulas are USED WITH TIME!! They are used 2 ways.

1: They can be used to identify the Rate Order By how they are graphed. For instance if you graph a 1st order reaction using the ln[A]t  (ln of concentration of reactant at some time period) in the y axis and the t (time)  in the x axis it will be linear with a negative slope.  If it is not linear with a negative slope then the reactant is not 1st order.

See the reference table below.

2: Once you identify the whether the RATE ORDER is 1 or 2 use the correct integrated rate law equation to solve either the time (t), initial concentration [A]0 , concentration of reactant after some time[A]t ,
or the rate constant, k.

What this lecture describes is the mathematics  (Calculus ) needed to solve for or Link Time with remaining reactants.  These important derivations will derive our Integrated Rate Law Formulas that are given to us in our reference tables.   They help us identify the order (or exponents) of our reactants in our Rate Law Equation just by graphing the changes of concentrations of the reactants in time during a chemical reaction.

Here they are in our reference tables:
 It is usually very helpful to utilize these equations when you arrange them into a linear equation.  1st Order:                   X   –>  Y                                         R = K [X]1                                                                 ln[A]t – ln[A]0 =  -kt                              ln[A]t  =   -kt   +    ln[A]0                                 y      =    mx  +      b                         (negative slope)  2nd Order:            X  +   X  –>  X2                                                                    1   –     1     =  kt                              [A]t    [A]0                             1     =  kt   +    1                                [A]t                  [A]0                                y     = mx  +   B                                                 (positive slope)

1: Integrated Rate Law formulas LESSON:

3: Review of the 2009 Rate Law Problem (using the new Integrated Rate Law Formulas):

Derivations of the 0th, 1st, and 2nd order Screencast lecture – optional lecture

Chenmistry Calculus (optional)- Why we need the differential Rate Laws

__________________________________________________________________                                   Jump to: Friday Homework / top       4/5 – Friday – B Day – 2, 3b/4 Lab

Main focus –

a) To Review the Integrated Rate law Equations with examples                                                    b) To determine the order of a reaction from experimental evidence – Lab

Period 2:

1.  A quick review of homework Frq using the New Integrated Rate law equations

2005B 2009 Kinetics quiz 2013 with college board and grodski keys.pdf

2. Lab 27 – Rate law with the Iodine Clock Reaction

Period 3b,4:

1.  A quick review of homework Frq using the New Integrated Rate law equations

2. Review of the RATE Law Skills

3. RATE LAW TEST

4.  Lab 27 – Rate law with the Iodine Clock Reaction

_______________________________________________________________________________

Lab 27 – The Determination of the Reactions Order of the Iodine Clock Reaction

Lab 27 – Rate Law of the Iodine Clock Reaction.pdf

Objectives:
1. To use the visual “end” of the reaction to measure the Rate of the reaction using different initial concentrations of the overall reaction.
2. To determine the overall chemical reaction from a proposed reaction mechanism
3. To determine the reaction orders and the Rate Law from the experimental data.
4.  To determine the rate determining step in the proposed mechanism based in the Rate Law.

The reaction is “clock” as it will give off a dark blue when it reached completion due to Iodine forming a complex with Starch.  This dark blue color is dramatic as it only occurs when one of the reactants runs out in one of the steps below:

IO3   +   3HSO3       →    I  +   3H+   +  3SO42-

8I  +   IO3 +   6H+    →  3I3   +  3H2O

I3   +  HSO3 +  H2O  →  3I  +  SO4-2  +  3H+

2 I3  +  starch  →  starch – I5 complex (blue)

We will use the time that it takes for the reaction to turn blue as the Rate of the reaction. Please be advised that the longer the time it takes for the reaction to complete represents a LOWER reaction Rate.

_____________________

TODAY’s NOTES:

Reference Table:
 This is the first order integrated formula.        This is the second order integrated formula.There is no zero order integrated formulas on the AP.This is the Arrhenius equation that ties activation energy ( Ea) and temperature to the rate law constant.

It is usually very helpful to utilize these equations when you arrange them into a linear equation.

1st Order:                       X    Y

R = K [X]1

ln[A]t – ln[A]0 =  -kt

ln[A]t  =   -kt   +    ln[A]0
y     =    mx  +      b

(negative slope)

2nd Order:                X  +   X    X2
R = K [X]2

–       =  kt
[A]t    [A]0

=  kt   +    1
[A]t                [A]0

y     = mx  +   B
(positive slope)

_________________________________________________                                                                                              jump to:  top              4/5 – Weekend Homework: –

1. Complete a short 5 question Rate law MC Form.

Catalysts and Activation Energy (Ea = Activation Energy)
The Arrhenius equation calculations are not on the AP but the concepts of how the k (Rate law Constant, like the equilibrium constant) is related to temperature.

2.  Please watch the Lecture on the derivation of the half – life formulas and lecture on the Activation Energy, Ea.

3. Complete the form below that is based on the 2 lectures.

4. Complete a 2 question FRQ (rate law and KSP). Please review with the AP Key or the Grodski key in the file below
(the keys are after the blank question)

Kinetics (rate law),Ksp Free Response, 2004B, 2009 FRQ .pdf

1 : Rate Law MC Questions Review Form: 3 submissions allowed.

>

2 : Half Life Derivations of the oth, 1st and 2nd order

2 : Activation Energy (Ea) Lecture.

3: Half Life / Arrhenius/ Ea Form 23-24 – ONLY 1 SUBMISSION!

C>