1 Chp 1: Welcome to the World of Chemistry & Chp 5: Measurement and calculation

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Chp 1: Welcome to the Chp 1: Welcome to the World of ChemistryWorld of Chemistry

&&Chp 5: Measurement Chp 5: Measurement

and calculationand calculation

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Goals:1. To understand the importance of learning chemistry

2. To define chemistry 3. To understand and illustrate scientific thinking 4. To describe the method scientists use to study nature5. To develop successful strategies for learning chemistry6. To show how very large or very small numbers can be expressed in

scientific notation 7. To learn the English, metric, and SI systems of measurement 8. To use the metric system to measure length, volume and mass 9. To learn how uncertainty in a measurement arises 10. To learn to indicate a measurement’s uncertainty by using significant

figures 11. To learn to determine the number of significant figures in a calculated

result12. To learn how dimensional analysis can be used to solve problems 13. To learn the three temperature scales, and how to convert between

them.14. To practice using problem solving techniques 15. To define density and its units

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The Language of The Language of ChemistryChemistryThe Language of The Language of ChemistryChemistry

• CHEMICAL ELEMENTSCHEMICAL ELEMENTS - - – pure substances that cannot be decomposed by pure substances that cannot be decomposed by

ordinary means to other substances.ordinary means to other substances.

SodiumBromine

Aluminum

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The Language of The Language of ChemistryChemistryThe Language of The Language of ChemistryChemistry

• The elements, The elements, their names, and their names, and symbols are given symbols are given on theon the PERIODIC PERIODIC TABLETABLE

• How many How many elements are elements are there?there? 117 elements have been identified117 elements have been identified

• 82 elements occur naturally on Earth82 elements occur naturally on EarthExamples: gold, aluminum, lead, oxygen, carbonExamples: gold, aluminum, lead, oxygen, carbon•35 elements have been created by scientists35 elements have been created by scientistsExamples: technetium, americium, seaborgiumExamples: technetium, americium, seaborgium

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The Periodic TableThe Periodic Table

Dmitri Mendeleev (1834 - 1907)Dmitri Mendeleev (1834 - 1907)

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Chemistry - the science that deals with the materials of the universe, and the changes that these materials undergo.

• Branches of ChemistryBranches of Chemistry• Organic chemistryOrganic chemistry

• Inorganic chemistryInorganic chemistry

• BiochemistryBiochemistry

• Physical chemistryPhysical chemistry

• An analytical chemistryAn analytical chemistry

Each Branch offers:Each Branch offers:• Many major areas of study for specializationMany major areas of study for specialization

• Several career opportunitiesSeveral career opportunities

• Also used in many other jobsAlso used in many other jobs

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1. Organic Chemistry

• Organic is the study of Organic is the study of matter that contains carbonmatter that contains carbon

• Organic chemists study the Organic chemists study the structure, function, structure, function, synthesis, and identity of synthesis, and identity of carbon compoundscarbon compounds

• Useful in petroleum Useful in petroleum industry, pharmaceuticals, industry, pharmaceuticals, polymerspolymers

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2. Inorganic Chemistry

• Inorganic is the Inorganic is the study of matter that study of matter that does NOT contain does NOT contain carboncarbon

• Inorganic chemists Inorganic chemists study the structure, study the structure, function, synthesis, function, synthesis, and identity of non-and identity of non-carbon compoundscarbon compounds

• Polymers, Polymers, MetallurgyMetallurgy

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3. Biochemistry

• Biochemistry is Biochemistry is the study of the study of chemistry in chemistry in living thingsliving things

• Cross between Cross between biology and biology and chemistrychemistry

• Pharmaceuticals Pharmaceuticals and geneticsand genetics

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4. Physical Chemistry

• Physical Physical chemistry is the chemistry is the physics of physics of chemistry… the chemistry… the forces of matterforces of matter

• Much of p-chem Much of p-chem is computationalis computational

• Develop Develop theoretical ideas theoretical ideas for new for new compoundscompounds

HONK if you passed p-chem

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5. Analytical Chemistry

• Analytical Analytical chemistry is the chemistry is the study of high study of high precision precision measurementmeasurement

• Find composition Find composition and identity of and identity of chemicalschemicals

• Forensics, quality Forensics, quality control, medical control, medical teststests

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The Scientific Method

•

• A hypothesis is just a fancy name for a prediction.

• An observation is something that can be observed with the senses and recorded – it is very different from a theory.

• Theories do NOT become laws. A law tells what happens; it summarizes an observed behavior. A theory is our attempt to explain why it happened.

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Scientific MethodScientific Method

1.1. State the problem clearly.State the problem clearly.

2.2. Gather information.Gather information.

3.3. Form a hypothesis.Form a hypothesis.

4.4. Test the hypothesis.Test the hypothesis.

5.5. Evaluate the data to form a conclusion.Evaluate the data to form a conclusion.

6.6. If data supports hypothesis, continue testing If data supports hypothesis, continue testing until enough evidence is gathered to form a until enough evidence is gathered to form a theory. (Theories can always be revised if theory. (Theories can always be revised if needed after further testing.) If data does not needed after further testing.) If data does not support hypothesis, go back to step 3.support hypothesis, go back to step 3.

7.7. Share the results.Share the results.

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Types of Observations and Types of Observations and MeasurementsMeasurements

• We makeWe make QUALITATIVEQUALITATIVE observations of reactions — observations of reactions — changes in color and physical changes in color and physical state.state.

• We also makeWe also make QUANTITATIVE QUANTITATIVE MEASUREMENTSMEASUREMENTS, which involve , which involve numbersnumbers..–UseUse SI unitsSI units — based on the — based on the

metric system (note: SI uses kg metric system (note: SI uses kg for mass instead of g)for mass instead of g)

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What is Scientific What is Scientific Notation?Notation?

• Scientific notation is a way of expressing really Scientific notation is a way of expressing really big numbers or really small numbers.big numbers or really small numbers.

• For very large and very small numbers, scientific For very large and very small numbers, scientific notation is more concise.notation is more concise.

Scientific notation consists of 2 parts:Scientific notation consists of 2 parts:• A number between 1 and 10A number between 1 and 10

• A power of 10A power of 10

N x 10N x 10xx

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To change standard form To change standard form to scientific notation :to scientific notation :

• Place the decimal point so that there is one non-zero Place the decimal point so that there is one non-zero digit to the left of the decimal point.digit to the left of the decimal point.

• Count the number of decimal places the decimal point Count the number of decimal places the decimal point has “moved” from the original number. This will be has “moved” from the original number. This will be the exponent on the 10.the exponent on the 10.

• If the original number was less than 1, then the If the original number was less than 1, then the exponent is negative. If the original number was exponent is negative. If the original number was greater than 10, then the exponent is positive.greater than 10, then the exponent is positive.

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ExamplesExamples

• Given: 289,800,000Given: 289,800,000• Use: 2.898 (Decimal point moved 8 places. Decimal Use: 2.898 (Decimal point moved 8 places. Decimal

number was bigger than 10, so exponent is positive.)number was bigger than 10, so exponent is positive.)• Answer:Answer: 2.898 x 102.898 x 1088

• Given: 0.000567Given: 0.000567• Use: 5.67 (Decimal point moved 4 places. Decimal Use: 5.67 (Decimal point moved 4 places. Decimal

number was smaller than one, so exponent is number was smaller than one, so exponent is negative)negative)

• Answer:Answer: 5.67 x 105.67 x 10-4-4

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To change scientific To change scientific notation to standard notation to standard

form…form…• Simply move the decimal point to the right (to Simply move the decimal point to the right (to

create a decimal number bigger than 10) for a create a decimal number bigger than 10) for a positive exponent of 10. positive exponent of 10.

• Move the decimal point to the left (to create a Move the decimal point to the left (to create a decimal number smaller than 1) for a negative decimal number smaller than 1) for a negative exponent of 10.exponent of 10.

(Use zeros to fill in places.)(Use zeros to fill in places.)

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ExampleExample• Given: 5.093 x 10Given: 5.093 x 1066

• Answer: Answer: 5,093,0005,093,000 (Exponent was (Exponent was positive, so decimal point moved 6 places positive, so decimal point moved 6 places to the right to get a decimal number to the right to get a decimal number greater than 10)greater than 10)

• Given: 1.976 x 10Given: 1.976 x 10-4-4

• Answer: Answer: 0.00019760.0001976 (Exponent was (Exponent was negative, so decimal point moved 4 negative, so decimal point moved 4 places to the left to get a decimal number places to the left to get a decimal number smaller than one)smaller than one)

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Learning Check

• Express these numbers in Express these numbers in Scientific Notation:Scientific Notation:

1)1) 405789405789

2)2) 0.0038720.003872

3)3) 30000000003000000000

4)4) 22

5)5) 0.4782600.478260

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Stating a MeasurementStating a Measurement

In every measurement there is aIn every measurement there is a

Number Number followed by a followed by a

Unit Unit from a measuring devicefrom a measuring device

The number should also be as precise as the measurement!The number should also be as precise as the measurement!

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Standards of MeasurementStandards of Measurement

When we measure, we use a measuring tool to When we measure, we use a measuring tool to compare some dimension of an object to a standard.compare some dimension of an object to a standard.

For example, at one time the For example, at one time the standard for length was the standard for length was the king’s foot. What are some king’s foot. What are some

problems with this standard?problems with this standard?

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SI measurementSI measurement• Le Système international Le Système international

d'unitésd'unités • The only countries that have not The only countries that have not

officiallyofficially adopted SI are Liberia adopted SI are Liberia (in western Africa) and Myanmar (in western Africa) and Myanmar (a.k.a. Burma, in SE Asia), but (a.k.a. Burma, in SE Asia), but now these are reportedly using now these are reportedly using metric regularlymetric regularly

• Metrication is a process that Metrication is a process that does not happen all at once, but does not happen all at once, but is rather a process that happens is rather a process that happens over time. over time.

• Among countries with non-Among countries with non-metric usage, the U.S. is the metric usage, the U.S. is the only only country significantly holding country significantly holding outout..

Information from U.S. Metric Association

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Chemistry In ActionChemistry In Action

On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat.

1 lb = 1 N

1 lb = 4.45 N

“This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.”

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UNITS OF UNITS OF MEASUREMENTMEASUREMENT

Use Use SI unitsSI units — based on the metric — based on the metric systemsystem

LengthLength

MassMass

VolumeVolume

TimeTime

TemperatureTemperature

Meter, mMeter, m

Kilogram, kgKilogram, kg

Seconds, sSeconds, s

Celsius degrees, ˚CCelsius degrees, ˚Ckelvins, Kkelvins, K

Liter, LLiter, L

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Mass vs. WeightMass vs. Weight

• Mass: Amount Mass: Amount of Matter (grams, of Matter (grams, measured with a measured with a BALANCE)BALANCE)

• Weight: Force Weight: Force exerted by the exerted by the mass, only mass, only present with present with gravity (pounds, gravity (pounds, measured with a measured with a SCALE)SCALE)

Can you hear Can you hear me now?me now?

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Metric PrefixesMetric Prefixes• Kilo-Kilo- means 1000 of that unit means 1000 of that unit

– 1 kilometer (km) = 1000 meters (m)1 kilometer (km) = 1000 meters (m)

• Centi-Centi- means 1/100 of that unit means 1/100 of that unit

– 1 meter (m) = 100 centimeters (cm)1 meter (m) = 100 centimeters (cm)

– 1 dollar = 100 cents1 dollar = 100 cents

• Milli-Milli- means 1/1000 of that unit means 1/1000 of that unit

– 1 Liter (L) = 1000 milliliters (mL)1 Liter (L) = 1000 milliliters (mL)

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Metric PrefixesMetric Prefixes

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Conversion FactorsConversion Factors

Fractions in which the numerator and Fractions in which the numerator and denominator are EQUAL quantities expressed denominator are EQUAL quantities expressed in different unitsin different units

Example: 1 in. = 2.54 cm

Factors: 1 in. and 2.54 cm

2.54 cm 1 in.

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Learning Check

Write conversion factors that relate each of Write conversion factors that relate each of the following pairs of units:the following pairs of units:

1. Liters and mL1. Liters and mL

2. Hours and minutes2. Hours and minutes

3. Meters and kilometers3. Meters and kilometers

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How many minutes are in 2.5 hours?

Conversion factor

2.5 hr2.5 hr x x 60 min 60 min = 150 min = 150 min

1 1 hr1 1 hr

cancelBy using dimensional analysis / factor-label method, By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the side up, and the UNITS are calculated as well as the

numbers!numbers!

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DIMENSIONAL ANALYSIS STEPS

1. Determine what unit is given and what unit you are seeking in the answer. This is often the most challenging step in this technique.

2. Write the unit you are seeking at the left margin of your paper with a “?”, and set it equal

to the unit(s) and the corresponding values of what was given. The given unit will be in the numerator—when in doubt put the original unit on top.

3. To cancel out the original unit, place that same unit in the next fraction’s denominator,

where it will be ready to cancel later.

4. Search for a unit definition that will get you closer to the unit you want in the final answer. This becomes the unit in the new fraction’s numerator. The resulting fraction or “unit definition” must be equivalent to one.

5. Continue this procedure until the unit has changed into the actual unit you are seeking in

your answer. When you arrive at the final unit, circle it.

6. Verify the definitions by reading the numerator and the denominator of each unit definition making sure they are equal. It is very easy to write 12 feet equals 1 inch, but when you read it, you will promptly catch your error.

7. Cancel the unit names after the unit definitions have all been verified. Only the units you

are seeking (those circled) should remain.

8. The last step is to cancel any common factors in the numbers; then multiply and divide the remaining numbers, completing the math.

The answer is a new number with its corresponding units.

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Sample Problem

• You have $7.25 in your pocket in You have $7.25 in your pocket in quarters. How many quarters do you quarters. How many quarters do you have?have?

7.25 dollars7.25 dollars 4 quarters 4 quarters

1 1 dollar1 1 dollar X = 29 quarters= 29 quarters

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You Try This One!You Try This One!If Jacob stands on Spencer’s If Jacob stands on Spencer’s

shoulders, they are two and a half shoulders, they are two and a half yards high. How many feet is that?yards high. How many feet is that?

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Learning Check

A rattlesnake is 2.44 m long. How A rattlesnake is 2.44 m long. How long is the snake in cm?long is the snake in cm?

How long is the snake in feet?How long is the snake in feet?

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Learning Check

How many seconds are in 1.4 days?

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Wait a minute!

What is What is wrongwrong with the following setup? with the following setup?

1.4 day x 1.4 day x 1 day 1 day x x 60 min 60 min x x 60 sec 60 sec

24 hr 1 hr 1 min24 hr 1 hr 1 min

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English and Metric English and Metric ConversionsConversions

• If you know ONE conversion for If you know ONE conversion for each type of measurement, you each type of measurement, you can convert anything!can convert anything!

• You must You must memorizememorize and use these and use these conversions:conversions:–Mass: 454 grams = 1 poundMass: 454 grams = 1 pound–Length: 2.54 cm = 1 inchLength: 2.54 cm = 1 inch–Volume: 0.946 L = 1 quartVolume: 0.946 L = 1 quart

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Learning CheckLearning Check

An adult human has 4.65 L of blood. How An adult human has 4.65 L of blood. How many gallons of blood is that?many gallons of blood is that?

Equalities: 1 quart = 0.946 L

1 gallon = 4 quarts

Your Setup:

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Dealing with Two Units – Honors Dealing with Two Units – Honors OnlyOnly

If your pace on a treadmill is 1.2 meters per If your pace on a treadmill is 1.2 meters per second, how many minutes will it take for you second, how many minutes will it take for you to walk a distance of 8450 feet?to walk a distance of 8450 feet?

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What about Square and Cubic What about Square and Cubic units? – Honors Onlyunits? – Honors Only

• Use the conversion factors you already Use the conversion factors you already know, but when you square or cube the know, but when you square or cube the unit, don’t forget to cube the number unit, don’t forget to cube the number also!also!

• Best way: Square or cube the ENITRE Best way: Square or cube the ENITRE conversion factorconversion factor

• Example: Convert 4.3 cmExample: Convert 4.3 cm33 to mm to mm33

4.3 cm4.3 cm33 10 mm 10 mm 33

1 cm 1 cm ( ) =

4.3 cm4.3 cm33 10 1033 mm mm33

1133 cm cm33

= 4300 mm3

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Learning CheckLearning Check• A Nalgene water bottle holds A Nalgene water bottle holds

1000 cm1000 cm33 of dihydrogen of dihydrogen monoxidemonoxide (DHMO). How many (DHMO). How many cubic decimeters is that?cubic decimeters is that?

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SolutionSolution

1000 cm1000 cm33 1 dm 1 dm 33

10 cm10 cm( ) = 1 dm= 1 dm33

So, a dmSo, a dm33 is the same as a Liter ! is the same as a Liter !

A cmA cm33 is the same as a milliliter. is the same as a milliliter.

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Buying Mulch• How many cubic yards of mulch will you need to cover a

20 ft by 30 ft play area to a depth of 6 inches?

• (Find volume of mulch in feet cubed, then convert to yards cubed.)

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Three Three targets with targets with three arrows three arrows each to each to shoot.shoot.

Accuracy and PrecisionAccuracy and Precision

Both accurate and precise

Precise but not accurate

Neither accurate nor precise

How do How do they they compare?compare?

AccuracyAccuracy - - Accuracy is how close a measured Accuracy is how close a measured value is to the value is to the actual (true) valueactual (true) value..

PrecisionPrecision - - Precision is how close the measured Precision is how close the measured values are values are to each other (how repeatable to each other (how repeatable the results are)the results are). Precision is influenced by how . Precision is influenced by how small of a measuring increment is used, and is small of a measuring increment is used, and is shown by how many significant digits are in theshown by how many significant digits are in the recorded answer.recorded answer.

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Significant FiguresSignificant Figures

The numbers The numbers reported in a reported in a measurement are measurement are limited by the limited by the measuring toolmeasuring tool

Significant figures in Significant figures in a measurement a measurement include the known include the known digits digits plus one plus one estimated digitestimated digit

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Equalities

State the same measurement in two different State the same measurement in two different unitsunits

lengthlength

10.0 in.10.0 in.

25.4 cm25.4 cm

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Always estimate ONE place past the smallest mark! Always estimate ONE place past the smallest mark!

Significant figures:Significant figures:

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Counting Significant FiguresCounting Significant Figures

RULE 1. All non-zero digits in a measured number RULE 1. All non-zero digits in a measured number are significant. are significant.

Number of Significant Figures38.15 cm38.15 cm 44

5.6 ft5.6 ft 22

65.6 lb65.6 lb

122.55 m122.55 m

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Leading ZerosLeading Zeros

RULE 2. Leading zeros in decimal numbers are RULE 2. Leading zeros in decimal numbers are NOTNOT significant. significant.

They just serve as placeholders (indicate the position of the They just serve as placeholders (indicate the position of the

decimal point).decimal point).Number of Significant Figures

0.008 mm0.008 mm 11

0.0156 oz0.0156 oz 33

0.0042 lb0.0042 lb

0.000262 mL 0.000262 mL

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Sandwiched (Captive) ZerosSandwiched (Captive) Zeros

RULE 3. Zeros between nonzero numbers are ALWAYS RULE 3. Zeros between nonzero numbers are ALWAYS

significant. significant. Number of Significant Figures

50.8 mm50.8 mm 33

2001 min2001 min 44

0.702 lb0.702 lb

0.00405 m0.00405 m

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Trailing ZerosTrailing Zeros

RULE 4. Trailing zeros in numbers without RULE 4. Trailing zeros in numbers without

decimals are NOT significant. They are only decimals are NOT significant. They are only

serving as place holders.serving as place holders.

Number of Significant Figures

25,000 in. 25,000 in. 22

200. yr200. yr 33

48,600 gal48,600 gal

25,005,000 g 25,005,000 g

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Counted numbers and definitions

Rule 5.• ACTUALLY COUNTED numbers are

EXACT, so they have an INFINITE number of significant digits.

• Definitions (which includes conversions between metric units) have an infinite number of significant digits.

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A. Which answers contain 3 significant figures?A. Which answers contain 3 significant figures?

1) 0.47601) 0.4760 2) 0.00476 2) 0.00476 3) 4760 3) 4760

B. All the zeros are significant inB. All the zeros are significant in

1) 0.00307 1) 0.00307 2) 25.300 2) 25.300 3) 2.050 x 10 3) 2.050 x 1033

C. 534,675 rounded to 3 significant figures isC. 534,675 rounded to 3 significant figures is

1) 535 1) 535 2) 535,000 2) 535,000 3) 5.35 x 10 3) 5.35 x 1055

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State the number of significant figures in each of the State the number of significant figures in each of the following:following:

A. 0.030 mA. 0.030 m

B. 4.050 LB. 4.050 L

C. 0.0008 gC. 0.0008 g

D. 3.00 mD. 3.00 m

E. 364 cars E. 364 cars


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Significant Numbers in CalculationsSignificant Numbers in Calculations

A calculated answer cannot be more precise than A calculated answer cannot be more precise than the measuring tool. the measuring tool.

A calculated answer must match the least precise A calculated answer must match the least precise measurement.measurement.

Significant figures are needed for final answers Significant figures are needed for final answers fromfrom

1) multiplying or dividing1) multiplying or dividing

2) adding or subtracting2) adding or subtracting

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Multiplying and Dividing

Round (or add zeros) to the calculated Round (or add zeros) to the calculated answer until you have the same number answer until you have the same number of significant figures as the measurement of significant figures as the measurement with the FEWEST significant figures.with the FEWEST significant figures.

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A. 2.19 X 4.2 =A. 2.19 X 4.2 = 1) 91) 9 2) 9.2 2) 9.2 3) 9.1983) 9.198

B. 4.311 ÷ 0.07 =B. 4.311 ÷ 0.07 = 1)1) 61.5861.58 2) 62 2) 62 3) 603) 60

C. C. 2.54 X 0.00282.54 X 0.0028 = = 0.0105 X 0.060 0.0105 X 0.060 1) 11.31) 11.3 2) 112) 11 3) 0.041 3) 0.041

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Adding and SubtractingAdding and Subtracting

The answer has the same number of decimal The answer has the same number of decimal places as the measurement with the fewest places as the measurement with the fewest decimal places.decimal places.

25.25.22 one decimal placeone decimal place

+ 1.+ 1.3434 two decimal placestwo decimal places

26.5426.54

answer 26.5answer 26.5 one decimal placeone decimal place

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In each calculation, round the answer to the In each calculation, round the answer to the correct number of significant figures.correct number of significant figures.

A. 235.05 + 19.6 + 2.1 = A. 235.05 + 19.6 + 2.1 =

1) 256.751) 256.75 2) 256.8 2) 256.8 3) 2573) 257

B. 58.925 - 18.2B. 58.925 - 18.2 ==

1) 40.7251) 40.725 2) 40.73 2) 40.73 3) 40.73) 40.7

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Temperature ScalesTemperature Scales• FahrenheitFahrenheit

• CelsiusCelsius

• KelvinKelvin

Anders Celsius1701-1744

Lord Kelvin(William Thomson)1824-1907

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Calculations Calculations Using Using TemperatureTemperature

• Generally require temp’s in Generally require temp’s in kelvinskelvins

• T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15

• Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K

• Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K

• Generally require temp’s in Generally require temp’s in kelvinskelvins

• T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15

• Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K

• Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K

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Temperature ScalesTemperature Scales

Notice that 1 kelvin = 1 degree Celsius1 kelvin = 1 degree Celsius

Boiling point Boiling point of waterof water

Freezing point Freezing point of waterof water

CelsiusCelsius

100 ˚C100 ˚C

0 ˚C0 ˚C

100˚C100˚C

KelvinKelvin

373 K373 K

273 K273 K

100 K100 K

FahrenheitFahrenheit

32 ˚F32 ˚F

212 ˚F212 ˚F

180˚F180˚F

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Fahrenheit Formula – Honors OnlyFahrenheit Formula – Honors Only

Freezing point of water: 0°C = 32°FFreezing point of water: 0°C = 32°F

Bioling point of water: 100°C = 212°FBioling point of water: 100°C = 212°F°F = 9/5 °C + 32 °F = 9/5 °C + 32

°C = 5/9 (°F - 32)°C = 5/9 (°F - 32)Convert 37 °C to °FConvert 37 °C to °F

Convert –40 °F to °C Convert –40 °F to °C

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DENSITYDENSITY - an important - an important and useful physical propertyand useful physical property

Density mass (g)volume (cm3)


Mercury

13.6 g/cm13.6 g/cm33 21.5 g/cm21.5 g/cm33

Aluminum

2.7 g/cm2.7 g/cm33

Platinum

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ProblemProblem A piece of copper has a A piece of copper has a mass of 57.54 g. It is 9.36 cm long, mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cmCalculate density (g/cm33).).



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StrategyStrategy1. Get dimensions in common units.1. Get dimensions in common units.

2.2. Calculate volume in cubic centimeters. Calculate volume in cubic centimeters.

3.3. Calculate the density.Calculate the density.

4. Round for correct number of significant digits.4. Round for correct number of significant digits.

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Osmium is a very dense metal. What is its Osmium is a very dense metal. What is its

density in g/cmdensity in g/cm3 3 if 50.00 g of the metal occupiesif 50.00 g of the metal occupies

a volume of 2.22cma volume of 2.22cm33??

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If blood has a density of 1.05 g/mL, how If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g many liters of blood are donated if 575 g of blood are given?of blood are given?

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What is the density (g/cmWhat is the density (g/cm33) of 48 g of a metal if ) of 48 g of a metal if the metal raises the level of water in a graduated the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? cylinder from 25 mL to 33 mL?

vol. of water:

vol. of metal:

25 mL 33 mL 25 mL 33 mL

Density of metal:Density of metal:

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Which diagram represents the liquid layers in the Which diagram represents the liquid layers in the cylinder?cylinder?

(K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)g/mL,) (W) water (1.0 g/mL)

1)1) 2) 2) 3) 3)

K

K

W

W

W

V

V

V

K

Documents

1 Chp 1: Welcome to the World of Chemistry & Chp 5: Measurement and calculation