from bed bugs to big bugs (actually both terms are incorrect)

http://www.stangnet.com/mustang-forums/members/dbmstng/

FROM BED BUGS TO BIG BUGS (actually both terms are incorrect)

http://www.calpoison.org/public/brown-recluse.jpg

http://en.wikipedia.org/wiki/68-95-99.7_rule

http://en.wikipedia.org/wiki/Empirical_rule

http://en.wikipedia.org/wiki/Image:Standard_deviation_diagram.svg


Kyle’s Girlfriend’s Hands

http://brown-recluse-spider.ascendedhealth.com/img/brown-recluse-spider-bite-pictures/img_BRS_thumb_day_3.jpg

http://www.emedicinehealth.com/slideshow_black_widow_brown_recluse_spiders/article_em.htm




Physical PropertiesKnowledge of physical properties allow substances to be observed and tested without changing the nature of the substance (chemical composition)

Example: melting ice and boiling water still leaves you with H2OAlso salt and water are easily mixed and separated and the salt and water still retain their physical characteristics.

Alloys (see handout) and solutions (salt water; air)

Other physical mixtures from the lab….Physical mixtures are characteristically non-uniform

Chemical PropertiesThese properties require the substance to “react” or be inherently altered so that it is different after the change.

Consider the “Observation Lab” reactionsAll required the combination of different substances such that physical properties after the change were very different than those before the change.Chemical mixtures (compounds) are always uniform

Mixture Separation LabThe mysterious mixture was separated by taking advantage of the physical properties of the components of the mixture.Iron - magneticIodine – sublimed and deposited on the cold surfaceSand – did not dissolve in water (insoluble) and particles were large enough to be trapped by the filter paperSalts – were all soluble and passed through the filter paper and were collected by rapid evaporation.

Based on your collected masses, calculate the percent composition of your mixture.

Magnetic material:Sublimed material:Filtered material:Dissolved material:Hint: divide your individual masses by the original

mass of your mixture and multiply by 100!You’re welcome!

Mixture Separation Lab Analysis

Compare your data to the data of classmates and the “true” values. What do you think about the data? Is it reliable (can we be confident that the data can be trusted?)

Explain the differences by identifying possible errors (human error is not allowed – be more specific) as you carried out the lab.

Identify the components of the mixture and the properties used to separate the mixture.

9) Holding the silver penny on the edges with tongs, place it in the hottest part of a burner flame. Pass it slowly through the flame.10) When the color changes again, plunge the penny into a beaker of water. Metals are hot.11) Make more coins.12) Clean up without sin (be impeccable).

Questions 1. Did you make gold? How could you prove it?2. What element gives the penny its silver color?3. What temperature does zinc melt? Look it up, lazy bums.4. What is an alloy?5. What is an alloy of copper and zinc? Copper and tin?6. Why are alloys helpful/useful?7. Draw a picture of what the particles of zinc did with the

particles of copper.

Matter Classification Assessment EvaluationHonors Chemistry

You will complete assessments prepared by your classmates.

Please evaluate it based on the following criteria (1-4 scale with 4 being most like and 1 being least like)Visually pleasing appearance (easy to read and understand)Challenging (it made you think)Length (it was great, not too short not too long)Accuracy (it effectively tested my level of knowledge of the content)Reliability (as an assessment tool, students with a similar understanding would get a similar score) Enjoyment Other complements and criticisms:

Mixture Practice Spark

• Complete the worksheet with your lab group, you will turn in whatever you have completed.

• Use the flowchart if you need it. It distinguishes matter by particle size and how materials are combined.

DOES IT LOOK LIKE ONE THING?

Is there only one ingredient in the composition?

Is it not on the periodic table?Is it made of more than one element?

Matter Classification based on particle size!primary questions

• Does it look like one thing?• Yes?• Homogeneous - from the same/one origin (homo – genesis)

– Mixtures (solutions and alloys) and Pure Substances– No?

• Heterogeneous - from different/multiple origins (hetero – genesis)– Mixture (suspensions and colloids)

Matter Primary Question:Does it look like one thing?

Yes Homogeneous No

Heterogeneous (mixture)

Homogeneous Question Is it made of one ingredient?

Yes Pure Substance

No Solution (mixture)

Heterogeneous Question Does it always look like more than one thing? Are the components

easily observed?

Yes suspensionsNo Colloids(From the Greek word for glue)

Colloidal Dispersions

Dispersed particles 1-100 nanometers in size

Dispersing Medium

Gas Liquid Solid

Gas Foam Foam

Liquid Aerosol Emulsion Gel

Solid Aerosol Sol Solid Sol

Dispersing Medium Gas Liquid Solid

Gas shaving cream,whipped cream

foam rubber,sponge,pumice

Liquid fogs, clouds,aerosol can spray

mayonnaise,milk, face cream

jelly, cheese,butter

Solid smoke,

car exhaust,airborne viruses

Gold in water,milk of

magnesia,river silt

alloys of metals(steel, brass)

Tyndall effect – helps distinguish between colloids and solutions (mixtures distinguished by the size of particles).

Gold in water

BThis liquid has particles that are big enough to disperse light.• Positive Tyndall

Effect• Colloid

Pure Substance Question:Is it unable to be separated into simpler forms of matter?

Yes Elements(Is it on the periodic table)

No Compounds

Solution Question:Is it made of metal?

Yes Alloy(see handout)

No

Element Question:Is it conductive, shiny, malleable, ductile? (periodic table)

Yes metal No nonmetal

Kind of? Metalloid/Semimetal

Compound Question: After mixing with water, is it conductive?

Yes Electrolyte (ionic and soluble)

No Nonelectrolyte (covalent or insoluble)

Electrolyte Question: Is the pH of the solution less than 7?

Yes Acids pH < 7No Bases pH >7 or Neutral pH = 7

pH = 7 Water and Salts

Nonelectrolyte Question:Is it a carbon based compound?

Yes OrganicNo No Inorganic

There are entire years of college chemistry curricula devoted just to these two categories of chemical compounds

Alchemy 101

Chromatography

SparkMeasure

the line on your measurement packet (in cm). Do not just copy the

measure of your neighbor

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

ALL Measurements in Science

English System

Metric System -The International System

use the

NOT the

Systems of Measurement

English System

Metric System -The International System

The U.S.

The rest of the World

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

SI Prefixes

SI Prefixes

mega 1 000 000

SI Prefixes

mega 1 000 000kilo 1 000

SI Prefixes

mega 1 000 000kilo 1 000centi 0.01

SI Prefixes

mega 1 000 000kilo 1 000centi 0.01milli 0.001

1 ml = 1 cm3

Say, "cubic centimeters"

NOT centimeters cubed

Important Derived Units

1 liter = 1 cubic decimeter, dm3



1 milliliter = 1 cubic centimeter, cm3



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

X10




1 dekameter = ? centimeters

X10




1 dekameter = 1000 centimeters

X10


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

divide by 10 with each step.

/10



1 centimeter = .01 meters

/10




1 centimeter = ? kilometers

/10




1 centimeter = .00001 kilometers

/10

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

cm3

cm

g oC

Use your measurement packet

This dust mite is about 450 micrometers long.

How many mites could fit lengthwise on a 2.5 meter mattress?

Yer bed is sooo cozy. We really ‘preciate yer hospeetality!

SPARK

The average mattress increases it’s mass nearly 4000g in 5 years.* *debatable

How many pounds of dead skin, mite and mite droppings is added to your sleep cushion per year? (2.2 lb = 1kg)

After 2 years, 10% of your pillow’s mass can be accounted for by dead mites and their droppings.* How many milligrams of a 0.85 kg pillow is dust-mite?

Sorry fer the mess, I know my poop makes you sneeze, but dang yer skin is delicious!

SPARK II

Metric Prefixes• You need to know them…• Their size (magnitude) and also their power of 10

– Examples: milli = 1000th or 10-3 or 3 decimal placeskilo = 1000 or 103 or 3 decimal places And how to change from one prefix to the other.Example: milli to kilo to centi to mega42 mg = 0.000042 kg = 4.2 cg = 0.000000042 Mg

4.2 x 101 mg = 4.2 x 10-5 kg = 4.2 x 100 cg = 4.2 x 10-8 Mg

1 X 106 meters - 1 megameter

Remember: Its a question of scale

1 000 000

1 X 105 meters - 100 kilometers

Its a question of scale

100 000

1 X 104 meters - 10 kilometers


10 000

1 X 103 meters - 1 kilometer


1 000

1 X 102 meters - 100 meters


100

1 X 101 meters - 10 meters


10

1 X 100 meters - 1 meter


1

1 X 10-1 meters - 0.1 meter - 10 cm


0.1

1 X 10-2 meters - 1 centimeter


0.01

1 X 10-3 meters - 1 millimeter


0.001

1 X 10-4 meters - 100 micrometers


0.000 1

1 X 10-5 meters - 10 micrometers


0.000 01

1 X 10-6 meters - 1 micrometer


0.000 001

Uncertainty in Measurement?

• Science may claim to be a search for “truth”, but never claims to be 100% confident that it knows the “facts”.

• Why not?• Where have scientists been mistaken?• Is it a question of scale? How big or

small your frame of reference is?

Uncertainty in Measurement• Estimation and Error

– Significant Figures– Reliability - Accuracy and Precision

Is this number accurate? Is it precise?

Is it the same as 2 g? 2.2 g? 2.24 g? 2.240 g? Which measurements are the most

precise? Most accurate?

The “Dart Board” on a line

• Below is the range of possible values with the “bullseye” or “true” value located somewhere amidst the data.

The “TRUTH” 2.1 2.3 2.4 2.5 2.6 2.8 2.9

X precise? X precise?N = 7Mean = 2.51 Median = 2.5

Uncertainty in MeasurementWhen enough measurements are made

there will be values that are larger and smaller than the mean. Those that are too far away from the other values, skew the mean and affect our understanding of the “truth”

All measurements are done by humans and are reflective of how confident the scientist is in their measurement tool and technique.

Every measurement is an “estimate”.

Depending on your measurement device you will not be 100% certain about the quantity being measured.

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.

105

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.

Uncertainty in Measurement• Estimation and Error

– Reliability - Accuracy and Precision– Significant Figures

How many sig figs (marked values plus one estimate) are in the measurements below

• 6.751 g __________

• 0.157 kg __________

• 28.0 ml __________

• 2500 m __________

• 0.070 g __________

• 30.07 g __________

• 0.0067 cm __________

43

24

2

32

Sig figs are the only digits that matter in a measurement.

Important Sig Fig Info

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



6 ml6.6 ml66.24 ml

124


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

123


always significant.


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



6006 ml6.02 g0.600 kg



6006 ml6.02 g0.600 kg

433


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



100 g0.001 ml0.000602 ml



113

100 g0.001 ml0.000602 m

Scientific Notation Only shows significant values!

• Number is separated into 2 parts– 1 must be a value between 1 and 10

PREFIX– 2 the power of ten that the prefix is

multiplied by to reflect the size of the valueMAGNITUDE


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 anINFINITE number ofsignificant figures.

Important

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

Find Sig Figs

• Sig figs are the only digits that matter in a measurement. They are always written to include all marked values plus your estimate.

• 142 g• 0.073 s• 1.071 cm• 70,810 kg• 5.00 mg• 55.320 pm• 1.010 fg

What are the correct measurements?

Rounding Rules - Wrong• When you round off, you change the value of the

number, unless you round off a zero. Remember that "rounding off" a zero does not change the value of the number being rounded.

• Following the old rules, you can round a number down in value four times (rounding with one, two, three, four) compared to rounding it upwards five times (five, six, seven, eight, nine).

• This cannot be allowed if we are to determine the TRUTH

Rounding Rules Wrong

• On average you would be changing values in the sample downwards 4/9ths of the time, compared to changing values in the sample upward 5/9ths of the time.

• This means the average of the values AFTER rounding would be greater than the average of the values BEFORE rounding.

• This is not acceptable as we search for the truth.

New Rules – Say What?

• If it is less than 5, drop it and all the figures to the right of it.

• If it is more than 5, increase by 1 the number to be rounded, that is, the preceding figure.

• If it is 5, round the number so that it will be even. Keep in mind that zero is considered to be even when rounding off.

Practice

UsingYOURcalculator.

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) =

588350significant 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

Spark Happy Friday 09.09.11• Please read the directions, complete the

worksheet and the sentence.

• This is a race. To the victor goes the spoils. To the losers go the smegma.

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.

WHAT DOES THIS MEAN???????

Consider what happens when you divide like terms in math….They cancel because dividing anything by itself = 1…..Right?

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

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


1 barrel

This line means divide by.


1 barrel

This line means multiply by.

Step 2: multiply by fractions equal to one.

1 barrel


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 = 42 gallons1 gallon = 4 quarts1 quart = 4 cups


1 barrel1 barrels

42 gallons


1 barrel1 barrels

42 gallons

Barrels have been converted to gallons.


1 barrel1 barrels

42 gallons

What units go here?


1 barrel1 barrels

42 gallons

gallons


1 barrel1 barrels

42 gallons

gallons

What units go here?


1 barrel1 barrels

42 gallons

gallons

quarts


1 barrel1 barrels

42 gallons

gallons

quarts

And the numbers are?



1 barrel1 barrels

42 gallons

1 gallon

4 quarts


1 barrel1 barrels

42 gallons

1 gallon

4 quarts

Gallons have become quarts.


1 barrel1 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

cups


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 dollarsCD

Multiply by fractions equal to 1:

What do we wantto cancel?

12 dollarsCD

Where does it go?

12 dollarsCD


12 dollarsCD

CD


What goes here?

12 dollarsCD

CD


12 dollarsCD

CD

songs


12 dollarsCD

1 CD

16 songs


12 dollarsCD

1 CD

16 songs

What are our units?


12 dollarsCD

1 CD

16 songs

dollars per song


12 dollarsCD

1 CD

16 songs

What goes here?


12 dollarsCD

1 CD

16 songs dollars


12 dollarsCD

1 CD

16 songs dollars

And here?


12 dollarsCD

1 CD

16 songs dollars

cents


12 dollarsCD

1 CD

16 songs 1 dollar

100 cents


12 dollarsCD

1 CD

16 songs 1 dollar

100 cents

What are our units?


12 dollarsCD

1 CD

16 songs 1 dollar

100 cents

cents per song

DO THE MATH:

12 dollarsCD

1 CD

16 songs 1 dollar

100 cents

75 cents / song

DO THE MATH:

Practice

Take your age and convert it into seconds! Do it!

Years to days to hours to minutes to seconds.

Percent Party!!!!!!!!

1. 7.9 g fat2. 1012 g milk3. 1.05% fat4. 10.6 g fat 0.0106 kg fat5. 546.48 g nonfat ingredients6. 0.211% fat7. 21.9 g sat fat8. 2.29 g unsat fat9. 7.49 g sat fat10. 624 g fat11. Polar Bear milk = 280.8 Cal Cow milk = 29.25 Cal12. 2.86 kg seawater13. 0.49 g Mg14. 537 kg magnesium sulfate

CooCooForCocoaSpark sorry for all the text!• The study was published in Chemistry Central Journal.• Comparing the antioxidants in chocolate vs. the so-called super-fruits –

acai berries, blueberries, cranberries, researchers at the Hershey Center for Health & Nutrition found that there was a greater antioxidant capacity per gram in cocoa powder than in fruit powders. Antioxidants inhibit the oxidation of cell molecules that turn into free radicals.

• Polyphenols and flavonols are the two main groups of antioxidants. Foods high in polyphenols and flavonols are the super foods and now cocoa powder has been added to this list.

While the flavonol content in most fruit powders averaged at less than 10 milligrams per gram of powder, it was found to be 30.1 milligram for one gram of cocoa powder. Per serving of 40 grams of dark chocolate had more than 500 milligrams of flavonols, cocoa powder with 400 milligrams and the fruit juices at one cup (220g) per serving, had less than 200 milligrams of flavonols. Convert each of these ratios to percent values so they can be more easily compared.

1,000 milligrams of polyphenol content was found in each serving of dark chocolate (40 grams). What is percent of dark chocolate is polyphenol?

• The flavonol content of cocoa powder was found to be higher than all of the fruit powders.

• Similar results were found when they compared dark chocolate and cocoa to fruit juices.

• The researchers studied the antioxidant activity for a 40 gram serving of dark chocolate and cocoa powder as compared with a one cup serving of fruit juice. With the exception of pomegranate juice, the dark chocolate showed significantly higher antioxidant activity per serving than the other fruit juices.

• Researchers have noted that the dark chocolate and cocoa powder used in the study contained natural or non-alkalized cocoa. Alkalization improves the taste, color and dispersion properties of the cocoa but destroys the polyphenolic compounds it contains. Bad news for hot chocolate lovers, though, is that their drink of choice offers little in the way of antioxidants (due to the way it's processed).

Communication in Science

• Statistical Analysis– Mean What was the average value? (bell

curve), aka “true” value, central tendency• How do other measurements compare to the mean?

– Percent Error how far off was the measurement from the accepted value?

SPARK

Monday, September 12, 2011Find the volume of a cube with a length measurement that has only 1 sig fig(ex: 3 cm)Find the volume of a cube with a length measurement containing 2 sig figs (ex: 3.3 cm) Find the volume of a cube that has a length measurement containing 3 sig figs (ex: 3.25 cm)Which measurement is most precise? Most accurate?

Dimensional Analysis Spark09/13/2011

Density is a conversion factor between the mass and volume of a sample.

Mercury has a density of 13.6 g/mL.What is the mass of 2.42 gallons of mercury? (1 gallon = 3.78 L)

Complete the Measurement Lab

Calibrate your balances before use.Send group reps up to deliver the data.

Part of your lab grade rests on getting me the data ASAP!If you are finished, work on the conversion worksheet (#1-19) that is due Wednesday

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

THIS IS A MEASURE OF ACCURACY!

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

theoreticalvalue

experimentalvalue

theoretical value% error =

_

X 100

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 =

_

X 100

% 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 =

_

X 100

Advanced Stats

• Mode, median, range• (average) Deviation from the mean• Standard Deviation – the mean of the

mean (Estimated Standard Deviation, <20) – how true is the “true” value?

• Normal Distribution


This is making me angry!!!!!!!!!!

What About Bad Data?Q test

• Q = abs. value of suspect value – closest value range of data

N 3 4 5 6 7 8 9 10 - 15

Qc 0.94 0.76 0.64 0.56 0.51 0.47 0.44 0.41

What About Bad Data?Q Test

Use only one time!Example: 9.43, 8.95, 8.97, 8.96, 8.93 g/cm3

N>15 Critical Q value is 2.6 x standard deviation

N 3 4 5 6 7 8 9 10 - 15

Qc 0.94 0.76 0.64 0.56 0.51 0.47 0.44 0.41

S = Standard Deviation• Mean of the mean• Square root of the sum of the squared

(devMean) divided by n-1

• In a normal distribution…• 68% of all measurements fall within one

standard deviation of the average. 95% of all measurements fall within two standard deviations of the average.


Steps for Standard Deviation

• Find mean of data• Find individual deviations from mean• Square all individual deviations from mean• Sum all squared deviations from mean• Divide by N or n-1• Square root the quotient

Practice Data: 100m Dash Times

X Time (sec) DvMean DvMean2 Mean

1 9.77 0.07 0.0049 9.90Truth?

2 9.78 0.06 0.0036 StDev

3 9.84 0.00 0.00 0.077

4 9.85 0.01 0.001 Con.

5 9.96 0.12 0.0144 0.04

6 10.20

Practice Data: 100m Dash Times

X Time (sec) DvMean DvMean2 Mean

1 9.77 0.07 0.0049 9.849.90 (Q)

2 9.78 0.06 0.0036 StDev

3 9.84 0.00 0.00 0.077

4 9.85 0.01 0.001 Con.

5 9.96 0.12 0.0144 0.04

6 10.20 Boo!

• About 68% of values drawn from a standard normal distribution are within one standard deviation away from the mean;

• About 95% of the values are within two standard deviations and

• About 99.7% lie within three standard deviations.

• This is known as the "68-95-99.7 rule" or the "empirical rule."

SD = 0.077

9.84

9.763

9.917 9.994

9.686

Distribution for 100 m Dash Times (s)




Confidence

• 2.16 +/- 0.05 cm3 at 95 % confidence means that there is a 95% probability the “true” value lies between 2.11 cm3 and 2.21 cm3

• IT DOES NOT MEAN THAT WE ARE CONFIDENT OF THE RESULT ONLY 95% OF THE TIME !

• About 68% of values drawn from a standard normal distribution are within one standard deviation away from the mean;

• About 95% of the values are within two standard deviations and

• About 99.7% lie within three standard deviations.

• This is known as the "68-95-99.7 rule" or the "empirical rule." 2.1

6 2.162.1

1

95.4% of the area under the curve

95.4% probability the true value lies here




Confidence depends on the size of your data sample (N) and the mean as it relates to the spread

of the data

• + or - Δ = t * S/NN-1 1 2 3 4 5 6 7 8 9 10 15 Infin

t 12.7 4.30 3.18 2.78 2.57 2.45 2.36 2.31 2.26 2.23 2.13 1.96

Reporting

• Mean = 1.015 g/cm3 with estimated deviation of 0.006 g/cm3

• Density = 1.015(6) g/cm3

• Density is 1.015 +/- 0.006 at 95% confidence limit• This is how science can tell if it is “right” or if it has

found the “truth” in nature.

Density Spark• An unknown metal was found to have a mass of 3.54 grams

and displaced 0.53 mL of water what is the density of the metal?

Known Densities (g/mL)Tellurium has a density of 6.4

Nickel has a density of 8.9Cerium has a density of 6.657

– What is the identity of the metal?– What is your percent error?– Is the data accurate?– Is it precise?– Where might errors exist in the data?Calculating density makes me really

happy!

DANG DIMENSIONAL ANALYSIS• The diameter of a palladium atom is 140 picometers; the

picometer is equal to 1 x 10-12 m; the equatorial diameter of the Earth is 40 075.02 km– How many Palladium atoms would it take to encircle the Earth at the Equator?– If one palladium atom weighs 1.77 x 10-22 g, then what is the mass of the

“palladium ring” circling the Earth?

• In America, a car’s gas efficiency is measured in miles per gallon. In Europe, it is measured in km/L. If your car’s gas mileage is 40.0 mi/gal, how many liters of would you need to complete a 142 km trip? – (1 km = 0.6214 miles; 1 gallon = 3.7884 L)

9/15/2011 Birthday Spark forTommy Lee Jones (p. 1)

• In America, a car’s gas efficiency is measured in miles per gallon. In Europe, it is measured in km/L. If your car’s gas mileage is 40.0 mi/gal, how many liters of gas would you need to complete a 142 km trip? – (1 km = 0.6214 miles; 1 gallon = 3.7884 L)

9/15/2011 Birthday Spark forTommy Lee Jones

Black Hole Density If the mass of the sun (m = 2 x 1033 g) were to collapse into a “spherical” black hole with a radius of 300 cm, then what is the density of the black hole? (Vsphere

= 4/3ér3)

A Volkswagen Beetle has a mass of 802 000 g. How many beetles would it take to equal this black hole sun of relative size?

http://apod.nasa.gov/htmltest/gifcity/rsgrow.mpg

Earth’s Density is 5.515 g/cm3

http://apod.nasa.gov/htmltest/gifcity/rsgrow.mpg

Friday Spark 09/16/2011

Phosphaturia is a medical condition of too much phosphorus in your urine. It can be a symptom of a kidney dysfunction. If 1 gallon of urine (density = 1.035 g/mL) produced 6.5 grams of phosphorus, then what is the percent concentration of phosphorus in the urine?(1 gallon = 3.78 L)

http://upload.wikimedia.org/wikipedia/commons/8/88/PhosphComby.jpg

http://en.wikipedia.org/wiki/File:Weewee.JPG

A number of these stars exploded as supernovae, producing black holes. Some of these, thought to weigh 10 to 20

times as much as the sun, shine brightly in X-rays (pink blobs) as they rob matter from companion stars.

Combining images from the Hubble Space Telescope and the Chandra X-ray Observatory, NASA offers a glimpse into a dazzling ring of black holes 430 million light years from Earth.

The image shows two galaxies, known collectively as Arp 147, that collided in the past, triggering a wave of star formation (blue ring in galaxy at right).

Measurement InvestigationsVerify the density of distilled water.What is the density of hot water?What is the density of cold water?Determine the density of other liquids like tap water,

saltwater, or ethanol.Determine the density of a known metal.Determine the density of a penny*.Calculate the thickness of a penny.What is the thickness of aluminum foil?

from bed bugs to big bugs (actually both terms are incorrect)

Documents

physical mixtures

physical characteristics

boiling water

water insoluble

beaker of water

sublimed material

data of classmates

particles of copper