Class Introduction

transcript

Help studentsdevelop the skill

of critical thinking.

CRITICAL thinking is theprocess of analyzing andapplying what you alreadyknow as a guide to action.

Critical thinking attemptsto intellectually figure something out.

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Putting namesand faces together.

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a search for

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The study of the properties of materials and the changes thatmaterials undergo.

You know the active ingredient in beer is C2H5OH.

Instead of saying ozone, you say O3.

You refer to the smell of nail polish remover as an acetone smell.

You ask for acetaminopheninstead of Tylenol.

When you hear the wordMOLE, you think of the number 6.02 X 1023

instead of a small furry animal.

You wash your hands BEFORE you go to the bathroom.

are needed to see this picture.Lab

Safety

What's wrong with this picture?

Safety glasses should ALWAYSbe worn during a lab.

Long hair should betied back.

Bulky and loose clothingAre dangerous in the lab.

Flammable materials mustbe kept away from lab burners.

You DON'T want to be like this!

Or this!

Horse-play has no place in

the lab.

If it occurs, those involvedwill be disqualified from the lab and given a ZEROfor the assignment.

You probably would not intentionallyharm someone, BUTaccidents can happen.

Horse-play has no place in

the lab.

Lack of pre-labpreparation

is the main threat tosafety in our lab.

Lack of pre-labpreparation

If you are unprepared, you will be unsure of what to do, waste time, and have a good chance of making a mistake that leads to a problem.

At the beginningof each lab

Pay close attention toverbal instructionsgiven at this time.

You will be given achance to ask questionsbefore we begin.

THIS is the time to ask...NOT after the lab starts.

Once the lab starts,you and your groupare on your own.

I will get involvedonly with issuesof SAFETY…

and that willcost your group

10 POINTS.

Water and acid combine in an EXOTHERMIC reaction.

Lab Safety 1 - 16 min

Lab Safety 2 - 24 min

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Lab Equipment

Erlenmeyer flask

Lab Equipment

Erlenmeyer flask ??

Lab Equipment

Erlenmeyer flask Beaker

Lab Equipment

Erlenmeyer flask ??Beaker

Lab Equipment

Erlenmeyer flask Test tubeBeaker

Lab Equipment

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Lab Equipment

GraduatedCylinder

Read the bottomof the meniscus.

Lab Equipment

GraduatedCylinder

??Read the bottomof the meniscus.

Lab Equipment

GraduatedCylinder

VolumetricFlaskRead the bottom

of the meniscus.

Lab Equipment

VolumetricPipet

Lab Equipment

VolumetricPipet

Lab Equipment

VolumetricPipet

Dropper Pipet

Lab Equipment

VolumetricPipet ??

Dropper Pipet

Lab Equipment

VolumetricPipet

MohrPipet

Dropper Pipet

Lab Equipment

SafetyPipetBulb

StandardPipetBulb

Lab Equipment

Draw liquid into the pipet with thebulb, NEVER by mouth like a straw.

Lab Equipment

Quickly removethe standard bulb and place your finger over the top to hold in the liquid.

Lab Equipment

Roll your fingerSLOWLY to allowliquid to flowfrom the pipet.

This takespractice!

Lab Equipment

Do not remove theliquid remaining inthe tip. MOST pipetsare calibrated toretain this amount.

Lab Equipment

Professional labstoday use "automatic"pipets with disposabletips.

Lab Equipment

A buret is a uniformcylinder designed toaccurately measurea volume of liquidtransferred to another vessel.

Lab Equipment

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Lab Equipment

EvaporatingDish

Lab Equipment

EvaporatingDish

Lab Equipment

EvaporatingDish

WatchGlass

Lab Equipment

EvaporatingDish

??WatchGlass

Lab Equipment

EvaporatingDish

Crucibleand Cover

WatchGlass

Lab Equipment

EvaporatingDish

Crucibleand Cover

WatchGlass

Lab Equipment

EvaporatingDish

Crucibleand Cover

WatchGlass

GlassStirring

Lab Equipment

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Lab Equipment

SupportRing

Lab Equipment

SupportRing

Lab Equipment

SupportRing

UtilityClamp

Lab Equipment

SupportRing

??UtilityClamp

Lab Equipment

SupportRing

WireGauze

UtilityClamp

Lab Equipment

WireTriangle

Lab Equipment

WireTriangle ??

Lab Equipment

WireTriangle

LabBurner

Lab Equipment

WireTriangle ??

LabBurner

Lab Equipment

WireTriangle Ring

LabBurner

Lab Equipment

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Lab Equipment

CrucibleTongs ??

Lab Equipment

CrucibleTongs

Test tubeHolder

Lab Equipment

CrucibleTongs

??Test tubeHolder

Lab Equipment

CrucibleTongs

StrikerTest tubeHolder

Lab Equipment

Thermometer

Lab Equipment

Thermometer

Lab Equipment

WashBottle

Thermometer

Lab Equipment

??WashBottle

Thermometer

Lab Equipment

Chemical Spoonor Spatula

WashBottle

Thermometer

Lab Equipment

FilterFunnel

Fold filter paperin half - twice -to make a conefor the funnel.

3 open edges on one side,1 open edge on the other.

Filter paper

Lab Equipment

Support the funnel with a ring stand.

NEVER allow the sample to go over the top of thefilter paper.

Lab Equipment

ElectronicBalance

Triple-beamBalance

NEVER place chemicalsdirectly on the balance pan!

The Bunsen Burner

Attach the burner hose tothe nozzle and turn on thegas at the wall FIRST.

The gas is fully onwhen the handleis PARALLEL with the nozzle.

Always use theburner with the nozzle inthis position.

Move the handleall the way ineither directionto turn it off.

When you HEARgas coming outof the burner,start the flamewith a striker.

The hottest part of the flameis at the top of the inner cone.

If there is only ONE flame,open the air vent at the bottom of the burner.

Clean-up is important for thesafety of those that come afteryou AND for the preservation of lab equipment.

Clean-up will vary from labto lab. Instructions will begiven for appropriate clean-upfor each lab.

NEVER put broken glassin the trash can.

Some chemicals can be putdown the drain - with LOTSof running water...

Other chemicals must beput in a waste container - AS DIRECTED.

NEVER put un-used chemicalsback into their original container.

ALWAYS read the labels on containers.

National Fire Protection Association

OSHA Approved Signs

Major safetyhazard

A hazardto safety

Possiblehazard

Safetyinformation

MSDSMaterial Safety Data Sheet

Provides all relevant safetyinformation about a chemical

Separating a Mixture

Chemistry is NOT a math class, but you will need yourOWN scientificcalculator.

ALL Measurements in Science

English System

Metric System -The International System

use the

NOT the

Measurement - 21 min

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SI Base Units

Mass kilogramLength meterTime secondEnergy JouleTemperature Celsius o

Amount of substance mole

Derived Units

Derived units involvemultiple base units.

Derived Units

Area = length 2

Derived Units

Area = length 2

Volume = length 3

Derived Units

Area = length 2

Volume = length 3

Density = mass / volume

Important Derived Units

1 liter = 1 cubic decimeter, dm3

1 milliliter = 1 cubic centimeter, cm3

Density of H2O = 1 gram / cm3

"cubic centimeters" NOT centimeters cubed

kilo = 1000

hecto = 100

deca = 10

the base = 1

deci = 0.1

centi = 0.01

milli = 0.001

kilo hecto deka 1 deci centi milli

When converting from abig prefix to a small prefix...

multiply by 10 with each step.

1 dekameter = 10 meters

1 dekameter = ? centimeters

1 dekameter = 1000 centimeters

When converting from asmall prefix to a big prefix...

divide by 10 with each step.

1 centimeter = .01 meters

1 centimeter = ? kilometers

1 centimeter = .00001 kilometers

All numbers in chemistryare measurements - so they MUST have units.

There are always limitations in themeasuring equipmentand in the ability of theperson using the equipment.

Measured quantities are properly reported in such a way that only the last digit is uncertain.

All digits of a measuredquantity, including the uncertain one, are calledsignificant figures.

The greater the numberof significant figures,the greater the implied certainty of the measurement.

This scale can reportonly 2significant figures.

The firstmeasured #is certainly 2.

The second #must beestimated.

The readingcould bereported as28 or 29...

But it could not be reported as28.5

A reading of 28.5 implies that oneswere measured and tenths estimated.

Important

When a calculation involvesmeasurements with differentnumbers of significant figures,the answer should have the same number of significantfigures as the LEAST in themeasurements.

Important

2 cm X 5.5 cm X 2.258 cm =

24.838 cm3

length X width X height = volume

Can we REALLY know the volume to thousandths of a cubic centimeter?

Important

2 cm X 5.5 cm X 2.258 cm =

24.838 cm3

What should be the answer?

Important

2 cm X 5.5 cm X 2.258 cm =

20 cm3

24 or 25 cm3

Rules for assigning significance

1. Digits other than zero are always significant.

6 ml6.6 ml66.24 ml

2. Rules for zeros:

2a. A single zero BEFORE the decimal point is NEVER significant.

0.6 ml

0.6 ml 1

2b. Final zeros AFTER a decimal point are

always significant.

0.6 ml6.0 ml6.60 ml

always significant.

0.6 ml6.0 ml6.60 ml

always significant.

2c. Zeros BETWEEN two significant figures are always significant.

6006 ml6.02 g0.600 kg

2d. Zeros used ONLY to space the decimal are never significant.

100 g0.001 ml0.000602 ml

100 g0.001 ml0.000602 m

2e. Scientific notation

6.02 X 10 23 atoms

Any digits BEFORE the Xare always significant.

6.02 X 10 23 atoms

The powers of 10 are never significant.

6.02 X 10 23 atoms

One last hint aboutsignificant figures:

Accepted equalities,like 1 foot equals 12 inches,are considered to have anINFINATE number ofsignificant figures.

Important

You will probably be requiredto used significant figures incollege chemistry class whenrounding off calculations.

Important

HHS chemistry class placesmore importance on usingthe OVERALL PROCESS than the minute details.....

Important

You may round off finalanswers liberally in this class...

as long as you show theprocess by which you GOT the answer.

Bring yourcalculatorto class.

Experimental error is acomparison of a value obtainedby measurement to anaccepted theoretical value.

The accepted theoretical value is either obtained from reference materialor calculated.

theoreticalvalue

experimentalvalue

theoretical value% error =

Exp Error Practice Problem.

A student determines experimentallythat the density of water is 0.85 grams per cubic centimeter.

Calculate the student's experimental error.

1.00 g0.85 g

1.00 g% error =

% error = 15 %

Exp Error Practice Problem.

Before drying, a sample weighs 5.6 g.After drying, it weighs 4.2 g.

The sample is known to contain3.0 grams of water.

Calculate the experimental error.

% error = 53 %

3.0 g1.4 g

3.0 g% error =

YOURcalculator.

Problem #1:

(10.25) (5.74 X 104) =

give the answer inscientific notation

Problem #1:

(10.25) (5.74 X 104) =

588350

Problem #1:

(10.25) (5.74 X 104) =

588350

significant figures?

Problem #1:

(10.25) (5.74 X 104) =

5.88 X 105

Problem #2:

(6.2 X 10-12) (3.87 X 109) =

give the answer inscientific notation

Problem #2:

(6.2 X 10-12) (3.87 X 109) =

0.023994

significant figures?

Problem #2:

(6.2 X 10-12) (3.87 X 109) =

2.4 X 10-2

Problem #3:

(6.02 X 1023) (1.05 X 1012) =

6.32 X 1035

Dimensional Analysis - the most important math in all of chemistry!!

Dimensional Analysis - used to convert from onetype of unit to another.

Dimensional Analysis - treats numbers andunits equally.

First - write what is given.

Then - multiply by fractionsequal to 1 to changethe units.

When - the only units NOT canceledare the units asked for,the problem is worked.

A problem:

How many cups of oilare in a barrel of oil?

Known equalities:

1 barrel = 42 gallons

1 gallon = 4 quarts

1 quart = 4 cups

Step 1: write what is given.

1 barrel

This line means divide by.

1 barrel

This line means multiply by.

Step 2: multiply by fractions equal to one.

1 barrel

What unitsgo here?

1 barrel

barrels

Now we'll be able tocancel barrels.

1 barrel

barrels

What unitsgo here?

1 barrel

barrels

gallons

1 barrel

barrels

gallons

What numbers will makethis fraction equal to 1?

1 barrel

1 barrels

42 gallons

1 barrel

1 barrels

42 gallons

Barrels have been converted to gallons.

1 barrel

1 barrels

42 gallons

What units go here?

1 barrel

1 barrels

42 gallons

gallons

1 barrel

1 barrels

42 gallons

gallons

What units go here?

1 barrel

1 barrels

42 gallons

gallons

quarts

1 barrel

1 barrels

42 gallons

gallons

quarts

And the numbers are?

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

Gallons have become quarts.

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

Are we done yet?

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

What units go here?

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

quarts

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

quarts

And here?

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

quarts

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

quarts

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 quart

4 cups

Quarts have become cups.

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 quart

4 cups

Have we worked the problem?

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 quart

4 cups

All units have been canceledexcept those we are looking for.

Step 3: DO THE MATH.

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 quart

4 cups

We are ready to punchthe buttons on the calculator.

1 barrel

1 barrels

42 gallons

1 gallon

4 quarts

1 quart

4 cups

1 barrel = 672 cups

Step 3: DO THE MATH.

Another problem:

A music CD costs 12 dollars.There are 16 songs on the CD. How many cents does each song cost?

What are we given:

What are we asked for:

What are we given: COST PER CD

What are we asked for: COST PER SONG

Write what is given:

12 dollars

Multiply by fractions equal to 1:

What do we wantto cancel?

12 dollars

Where does it go?

12 dollars

What goes here?

12 dollars

16 songs

12 dollars

16 songs

What are our units?

12 dollars

16 songs

dollars per song

12 dollars

16 songs

What goes here?

12 dollars

16 songs dollars

12 dollars

16 songs dollars

And here?

12 dollars

16 songs dollars

12 dollars

16 songs dollars

12 dollars

16 songs 1 dollar

100 cents

12 dollars

16 songs 1 dollar

100 cents

What are our units?

12 dollars

16 songs 1 dollar

100 cents

cents per song

DO THE MATH:

12 dollars

16 songs 1 dollar

100 cents

75 cents / song

DO THE MATH:

Chemistry - 44 min

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Class Introduction

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