chemistry lab by lin wozniewski [email protected]. disclaimer this presentation was prepared using draft...
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DisclaimerDisclaimer
This presentation was prepared using draft This presentation was prepared using draft rules.rules. There may be some changes in the There may be some changes in the final copy of the rules.final copy of the rules. The rules which will The rules which will be in your Coaches Manual and Student be in your Coaches Manual and Student Manuals will be the official rulesManuals will be the official rules
What do they need to be able to do What do they need to be able to do every year every year? every year every year?
Interpretation of Interpretation of experimental data experimental data (tabular and/or graphic) (tabular and/or graphic)
Observation of an Observation of an experiment set up and experiment set up and running running
Computer or calculator Computer or calculator sensors/probes sensors/probes
Stoichiometry : mole Stoichiometry : mole conversions and conversions and percentage yieldpercentage yield
Nomenclature and Nomenclature and formula writing - symbols formula writing - symbols and charges for the and charges for the following ions by memory: following ions by memory: nitrate, carbonate, nitrate, carbonate, phosphate, acetate, phosphate, acetate, sulfate, ammonium, sulfate, ammonium, bicarbonate, and bicarbonate, and hydroxide (“ite” forms of hydroxide (“ite” forms of “ates” listed) “ates” listed)
SafetySafetyStudents must wear:Students must wear: Closed shoesClosed shoes Slacks or skirts that come to the anklesSlacks or skirts that come to the ankles Long-Sleeved Shirt (if wearing a lab apron)Long-Sleeved Shirt (if wearing a lab apron) Lab coat or lab apronLab coat or lab apron Indirect vent or unvented chemical splash Indirect vent or unvented chemical splash
proof goggles. No impact glasses or proof goggles. No impact glasses or visorgogs are permittedvisorgogs are permitted
What the Students Should BringWhat the Students Should Bring
Safety gearSafety gear
Something to write withSomething to write with
What the Students Should Not BringWhat the Students Should Not Bring
Anything else
This includes notes
What the Supervisor ProvidesWhat the Supervisor Provides
Everything the student will needEverything the student will need This may include:This may include:
GlasswareGlasswareReagentsReagentsBalancesBalancesHot platesHot platesThermometersThermometersProbesProbesMagnetsMagnetsStirrersStirrers
How to prepare participantsHow to prepare participantsMake sure students read the directions and pay Make sure students read the directions and pay particular attention to the description of the particular attention to the description of the event (The Competition) event (The Competition)
Have them do many experiments together Have them do many experiments together
Have them determine their individual strengths Have them determine their individual strengths
Divide (and conquer) tasks during competition Divide (and conquer) tasks during competition
Check each other’s work Check each other’s work
How to prepare participantsHow to prepare participants
Get as many lab books from your Get as many lab books from your chemistry teacher as possible & have chemistry teacher as possible & have students explore labs by topic and do the students explore labs by topic and do the ones that appear consistently ones that appear consistently
Changes for 2013 Changes for 2013
1 new topic & 1 new topic & 1 old topic1 old topic: : PeriodicityPeriodicity EquilibriumEquilibrium
Equilibrium ActivitiesEquilibrium Activities
Students should be able to write equilibrium Students should be able to write equilibrium reactionsreactionsPredict the direction of a reaction using Le Predict the direction of a reaction using Le Châtelier’s Principle.Châtelier’s Principle.Calculate an equilibrium constant.Calculate an equilibrium constant. Use equilibrium constants to determine Use equilibrium constants to determine concentrationsconcentrationsAt the state and national levels knowledge and At the state and national levels knowledge and application, knowledge/application of application, knowledge/application of equilibrium to separate chemicals may be equilibrium to separate chemicals may be includedincluded
PeriodicityPeriodicityStudents should understand the periodic nature Students should understand the periodic nature of the elements. Knowledge about periodicity of the elements. Knowledge about periodicity should be demonstrated conceptually (by should be demonstrated conceptually (by predicting or explaining trends) or where predicting or explaining trends) or where possible experimentally (by collecting and/or possible experimentally (by collecting and/or accounting for data). Topics may include the accounting for data). Topics may include the following:following:
Physical properties (e.g. atomic & ionic radii, ionization Physical properties (e.g. atomic & ionic radii, ionization energy, melting point, electro-negativity, etc.)energy, melting point, electro-negativity, etc.)
Electronic structure and bonding formation (e.g. ionic vs. Electronic structure and bonding formation (e.g. ionic vs. covalent, charges on ions, etc.)covalent, charges on ions, etc.)
Chemical properties (e.g. precipitate formation, solubility, Chemical properties (e.g. precipitate formation, solubility, reactions with acids, etc.)reactions with acids, etc.)
Equilibrium Activities Equilibrium Activities Use a titration/data of a weak acid/base Use a titration/data of a weak acid/base with a strong acid/base to calculate an with a strong acid/base to calculate an equilibrium constant.equilibrium constant.
Investigate an equilibrium reaction and Investigate an equilibrium reaction and determine what happens when it is determine what happens when it is stressed.stressed.
Stoichiometry of equilibrium reactions. Stoichiometry of equilibrium reactions.
Equilibrium ActivitiesEquilibrium Activities
Construct/use a standard absorption Construct/use a standard absorption curve to determine an equilibrium curve to determine an equilibrium constant. constant.
Use a calorimeter to predict a curve. Use a calorimeter to predict a curve. Use a syringe to verify gas laws. Use a syringe to verify gas laws.
Equilitrium ActivitiesEquilitrium Activities
http://education.ti.com/educationportal/activityexchange/activity_list.do?cid=us
http://chemtutor.com/redox.htm
Periodic ActivitiesPeriodic ActivitiesTrends in electronegativityTrends in electronegativity Small pieces of metal have a drop of another metal’s ion put Small pieces of metal have a drop of another metal’s ion put
on them to see if there is a reaction or noton them to see if there is a reaction or not Or a small piece of metal is dropped into a test tube Or a small piece of metal is dropped into a test tube
containing another ion’s metal to see if there is a reaction or containing another ion’s metal to see if there is a reaction or not.not.
Trends in reactivity with acidsTrends in reactivity with acids Demonstrations can be done in water of Demonstrations can be done in water of Lithium, ,
Sodium, Potassium, Cesium, and RubidiumSodium, Potassium, Cesium, and Rubidium Students can then be given Magnesium, Calcium, Students can then be given Magnesium, Calcium,
and Aluminum to put in water or mild acid . and Aluminum to put in water or mild acid . Demonstrations can also be done on Strontium.Demonstrations can also be done on Strontium.
Periodic ActivitiesPeriodic ActivitiesTrends in Acid/Base propertiesTrends in Acid/Base properties
Small pieces of Magnesium, Calcium, Sulfur, and red Small pieces of Magnesium, Calcium, Sulfur, and red Phosphorus can be burned, put in water, and then the Phosphorus can be burned, put in water, and then the solution tested with a pH meter to see the trends in the solution tested with a pH meter to see the trends in the oxides producing acids or basesoxides producing acids or bases
Trends in reactivity of halidesTrends in reactivity of halides Chlorine water, bromine water, and iodine water Chlorine water, bromine water, and iodine water
can be put in solutions of sodium chloride, sodium can be put in solutions of sodium chloride, sodium bromide, and sodium iodide and a little hexane bromide, and sodium iodide and a little hexane added. The resulting color of the organic solvent added. The resulting color of the organic solvent will pick up the halogen to show if there has been will pick up the halogen to show if there has been a reaction or not.a reaction or not.
Periodic ActivitiesPeriodic Activities
The Periodic Properties application for the The Periodic Properties application for the Texas Instrument calculators can be used Texas Instrument calculators can be used to graph the trends in the periodic table in to graph the trends in the periodic table in terms of electronegativity, atomic radius, terms of electronegativity, atomic radius, ionization energy, density, etc.ionization energy, density, etc.
Resources: TI Activity Exchange Resources: TI Activity Exchange
http://education.ti.com/calculators/http://education.ti.com/calculators/downloads/US/Activities/Search/Subject?downloads/US/Activities/Search/Subject?s=5023&sa=5028&t=5099s=5023&sa=5028&t=5099
ScoringScoring
50% 50% EquilibriumEquilibrium
50% Periodicity50% Periodicity
ResourcesResources
://mypage.iu.edu/~lwoz/socrime/index.htm://mypage.iu.edu/~lwoz/socrime/index.htm
For Lesson Plans for classroom useFor Lesson Plans for classroom use http://mypage.iu.edu/~ For Event Supervisorshttp://mypage.iu.edu/~ For Event Supervisors http lwoz/socrime/index.htmhttp lwoz/socrime/index.htm
Questions???Questions???
Thank youThank you
Time to play!
4 basic problems to solve Periodic Properties using TI calculator and
Periodic Table application Equilibrium-Colorimetric Determination of an
Equilibrium Constant & Le Châtelier’s Le Châtelier’s Principle Principle
Periodic Properties using TI pH probe Equilibrium-Determine the Equilibrium
constant of a weak acid.
Periodic Properties ApplicationTurn the calculator on
Arrow over to “My Documents”
Press the center button of the arrows
Arrow down to “Periodicity of Properties”
Press the center button to start the app.
Hit control & the right arrow button
Here we have a complete periodic table that can be referred to
Hit control & the right arrow button again
Periodic Properties ContinuedYour center button is now a mouse.At the bottom of the page is a graph of the properties of elements 1-60You can change what is graphed on the Y axis by moving the mouse over the Y axis label and pressing the center buttonWe want to find the elements in the 4th energy level that have atomic radii between Ru and Cd.Move the mouse over any data point & it will tell you the atomic # and radius
Periodic Properties ContinuedDon’t remember the atomic numbers of Ru and Cd?
Move the arrow over the 1.2 tab at the top and hit the center button.
Look for Ru & Cd. What do you notice about what energy level they are in?
Move the arrow over the 1.3 tab at the top and press the center button
Move the arrow until you find element 44. Note the radius. Move till you find element 48. Note the radius
Periodic Properties ContinuedNow move from the 5th energy level to the 4th.
Which elements have radii between these two?
Now move the mouse to the Y axis label and press the center button.
Arrow down to first ionization energy.
Repeat the process.
Repeat for Electronegativity
Repeat for Density
What is the mystery substance?
EquilibirumPipette 5 ml of .002 M Fe(NO2)3 into a 10 ml graduated cylinder Pipette 1 ml of .002 M KSCN into the cylinder.Fill to 10 ml with DI, put in a containerPour into a cuvette
Pipette 5 ml of .002 M Fe(NO2)3 into a 10 ml graduated cylinder Pipette 2 ml of .002 M KSCN into the cylinder.Fill to 10 ml with DI, put into containerPour into a cuvette
Equilibrium Cont.Pipette 5 ml of .002 M Fe(NO2)3 into a 10 ml graduated cylinder Pipette 3 ml of .002 M KSCN into the cylinder.Fill to 10 ml with DI, put in containerPour into a cuvette
Pipette 5 ml of .002 M Fe(NO2)3 into a 10 ml graduated cylinder Pipette 5 ml of .002 M KSCN into the cylinder.Put in containerPour into a cuvetteFill one cuvette with DI
Equilibrium Con’t.Equilibrium Con’t.Attach colorimeter to TI using EasyLink.Attach colorimeter to TI using EasyLink.
Set colorimeter to 470 nm (if necessary) by Set colorimeter to 470 nm (if necessary) by pushing blue buttons on colorimeter right or left pushing blue buttons on colorimeter right or left until light under 470 nm lit.until light under 470 nm lit.
Put the cuvette of DI in and hit the “calibrate” Put the cuvette of DI in and hit the “calibrate” button on the colorimeterbutton on the colorimeter
Hit “Menu” button on the calculatorHit “Menu” button on the calculator
Click on “Experiment”Click on “Experiment”
Arrow down to “Collection Mode” & clickArrow down to “Collection Mode” & click
Arrow down to “Events with Entry” & clickArrow down to “Events with Entry” & click
Equilibrium Con’tEquilibrium Con’tTitle it ConcentrationTitle it Concentration
Tab to UnitsTab to Units
Put down molarity for unitsPut down molarity for units
Determine your initial unreacted SCNDetermine your initial unreacted SCN-- molarity molarity
Put 1Put 1stst cuvette in and click on icon in lower left cuvette in and click on icon in lower left hand corner. Click on Start in lower left hand hand corner. Click on Start in lower left hand corner. When reading stabilizes, click on corner. When reading stabilizes, click on camera icon. Put in the concentration you have camera icon. Put in the concentration you have determined in whole numbers.determined in whole numbers.
Equilibrium ContinuedEquilibrium ContinuedPut in 2Put in 2ndnd cuvette & repeat cuvette & repeat
Put in 3Put in 3rdrd cuvette and repeat cuvette and repeat
Click on stop collectingClick on stop collecting
Click on the blue ctrl button and the save Click on the blue ctrl button and the save button.button.
Name your graph somethingName your graph something
Click on the menu button and arrow down to Click on the menu button and arrow down to analyzeanalyze
Arrow over and down to curve fit.Arrow over and down to curve fit.
Click on linearClick on linear
Equilibrium con’tEquilibrium con’t
Determine slope of the line. Since according to Determine slope of the line. Since according to the Beer Lambert law A=abc, bc=slope of the the Beer Lambert law A=abc, bc=slope of the line. (we are deliberately attempting to force line. (we are deliberately attempting to force equilibrium to completion by making equilibrium to completion by making concentration of Iron(III) much higher that concentration of Iron(III) much higher that thiocyanate, thus the concentration of the thiocyanate, thus the concentration of the thiocyanate = the concentration of the complex.thiocyanate = the concentration of the complex.
Since we entered whole numbers instead of the Since we entered whole numbers instead of the actual concentrations, we need to divide by actual concentrations, we need to divide by 0.0001 to get the real slope.0.0001 to get the real slope.
Equilibrium con’tEquilibrium con’tPut in the 4Put in the 4thth cuvette and determine the cuvette and determine the absorbance. Write it down.absorbance. Write it down.
Pour the contents of the cuvette into a test Pour the contents of the cuvette into a test tube and put in either a hot water or a cold tube and put in either a hot water or a cold water bath. After 5 minutes determine the water bath. After 5 minutes determine the Absorbance.Absorbance.
Repeat in the other bath or exchange data Repeat in the other bath or exchange data with someone who did the other one.with someone who did the other one.
We can use this information to determine if We can use this information to determine if the reaction is endothermic or exothermicthe reaction is endothermic or exothermic
Equilibrium con’tEquilibrium con’tk=[FeSCNk=[FeSCN+2+2[/[Fe[/[Fe+3+3][SCN][SCN--] (all at equilibrium)] (all at equilibrium)
We know can determine the original We know can determine the original concentrations of the unreacted reagentsconcentrations of the unreacted reagents
We can determine the concentration of the We can determine the concentration of the complex at equilibrium by dividing the complex at equilibrium by dividing the absorbance of the 4absorbance of the 4thth tube be the slope of tube be the slope of the linethe line
We can subtract the concentration of the We can subtract the concentration of the complex from the concentrations of the complex from the concentrations of the original reagents and find K.original reagents and find K.
Periodicity-Reaction typesPut 2 ml of water into each of 4 vials
Add a piece of MgO to one vial, cover & shake
Add a piece of CaO to a second vial, cover, & shake
Use the straw to blow into a third vial, cover, & shake
Hold the 4th vial so that as soon as a match is struck, the strike smoke can be captured, cover and shake
Insert the pH probe in each vial
Periodicity-Reaction Types
What type of elements are Mg & Ca?
What types of elements are S and C?
What types of compounds do metal oxides form when they react with water?
What types of compounds do non-metal oxides form when they react with water?
EquilibriumEquilibriumMeasure 10 ml of the unknown acid into a beaker.Measure 10 ml of the unknown acid into a beaker.
Determine the volume of a drop of water from the Determine the volume of a drop of water from the pipette by counting how many drops it takes to make pipette by counting how many drops it takes to make up a ml in the graduated cylinder.up a ml in the graduated cylinder.
Attach a pH probe to the TI calculator.Attach a pH probe to the TI calculator. Hit “Menu” Hit “Menu” buttonbutton
Click on “Experiment”Click on “Experiment”
Arrow down to “Collection Mode” & clickArrow down to “Collection Mode” & click
Arrow down to “Events with Entry” & clickArrow down to “Events with Entry” & click
Title it pH.Title it pH.
Use units of drops or ml.Use units of drops or ml.
Click on “Start” buttonClick on “Start” button
Equilibrium con’t.Equilibrium con’t.When pH stabilizes click on cameraWhen pH stabilizes click on camera
Enter 0 drops or ml.Enter 0 drops or ml.
Add 1 drop .100 M NaOH & take a readingAdd 1 drop .100 M NaOH & take a reading
Continue adding NaOH and taking a reading Continue adding NaOH and taking a reading after each 5 drops.after each 5 drops.
How many drops (ml) did it take to get to the How many drops (ml) did it take to get to the endpoint?endpoint?
What is half that volume?What is half that volume?
Equilibrium con’t.Equilibrium con’t.
What is the pH at the half way point?What is the pH at the half way point?
Since the kSince the kaa=[H=[H++][An][An--]/[HAn] (yes I am only ]/[HAn] (yes I am only
using monoprotic acids for this level), at using monoprotic acids for this level), at the half way point the [Anthe half way point the [An--]=[HAn]]=[HAn]
Taking the negative log of both sides, Taking the negative log of both sides, pH=pKpH=pKaa..
We then take the antilog of the negative of We then take the antilog of the negative of the pH at the half-way point to find the Kthe pH at the half-way point to find the Kaa..