Unit A: Introduction: Matter and Measurement · 2018. 10. 15. · Gravity & Vacuum Filtration...

Unit A: Introduction:Matter and Measurement

Chapter 1Bonus points may be available for

suggesting good wrong answers for future use.

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2

What element is represented by the red piece of the pies?

1. N2. H3. Na

4. O5. Mg6. Si

7. F8. C9. Zn

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3

What element is represented by the red piece of the pies?

1. N2. H3. Na

4. O5. Mg6. Si

7. F8. C9. Zn

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4

Which two elements make up the remaining 28% of the human body?

1. N2. H3. Na

4. Cl5. Mg6. Si

7. F8. C9. Zn

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5

Which elements make up the remaining 28% of the human body?

1. N2. H3. Na

4. Cl5. Mg6. Si

7. F8. C9. Zn

CxHyOz organic compounds make up the proteins, fats and oils, and DNA throughout the body.

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What element makes up the remaining 28.5 % of the earth’s crust?

1. N2. He3. Na

4. Cl5. Mg6. Si

7. F8. He9. Zn

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What element makes up the remaining 28.5 % of the earth’s crust?

1. N2. He3. Na

4. Cl5. Mg6. Si

7. F8. He9. Zn

Silicon and oxygen combine to make SiO2 silicon dioxide, which is quartz, and ends up as a major component of glass. SiO2 is a network covalent solid

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Select the phase and properties that are NOT correct. Select all that apply.1. Solid - definite shape, constant density2. Gas - compressible, fluid3. Vapor - definite volume, indefinite shape4. Solid - rigid, incompressible5. Liquid - definite volume, indefinite shape6. Gas - variable density, fills its container7. Liquid - compressible, fluid8. All are correct.

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Select the phase and properties that are NOT correct. Select all that apply.1. Solid - definite shape, constant density2. Gas - compressible, fluid3. Vapor - definite volume, indefinite shape4. Solid - rigid, incompressible5. Liquid - definite volume, indefinite shape6. Gas - variable density, fills its container7. Liquid - compressible, fluid8. All are correct.

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On your white board, write a short question that would be suitable for the pink box.

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On your white board, write a short question that would be suitable for the pink box.

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On your white board, write a short question that would be suitable for the blue box.

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Same Scheme, Arranged Differently

the most fundamentalform of matter

element

in a fixed ratio

chemically combined

2 or more elements

compound

Pure Substance

heterogeneous homogeneousaka: solution

in a variable ratio

physically mixed

2 or more substances

Mixture

All Matter

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Which box(es) contain(s) only elements? Select as many as appropriate.

1

2

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Which box(es) contain(s) only elements?A, in which the particles are atomsB, in which the particles are molecules.

A

B

CD

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Which box(es) contain(s) a pure substance?

1

2

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Which box(es) contain(s) a pure substance?A and B which are elements and C which is a compound.Only D is a mixture of both elements and a compound and the particles are both atoms and molecules.

A

B

CD

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What changes that may occur during a chemical change do not change ever during a physical change? Select all that apply.

1. color2. shape3. appearance4. identity

5. temperature6. mass7. density8. melting point

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What changes in a chemical change that does not change during a physical change? Select all that apply.

1. color2. shape3. appearance4. identity

5. temperature6. mass7. density8. melting point

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This diagram best illustrates

1. the Law of Constant Composition.2. the Law of Conservation of Mass.3. the First Law of Thermodynamics4. the Law of Definite Proportions5. the Law of Mass Action

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This diagram best illustrates

1. the Law of Constant Composition.2. the Law of Conservation of Mass.3. the First Law of Thermodynamics4. the Law of Definite Proportions5. the Law of Mass Action

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The Various Ways You Can State the Law of Conservation of Mass

• There is no detectable change in the total mass of materials when they react chemically to form new materials.

• The mass of the products will equal the mass of the reactants in a chemical reaction.

• During a chemical reaction, matter is neither created nor destroyed.

• The mass of what you start with is what you’ll finish with in a chemical reaction.

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This experiment might be used for

1. the Law of Constant Composition.2. the Law of Conservation of Mass.3. the First Law of Thermodynamics4. the Law of Definite Proportions5. the Law of Multiple Proportions6. measuring % of the reacting part of air7. the Law of Mass Action

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This experiment might be used for

1. the Law of Constant Composition.2. the Law of Conservation of Mass.3. the First Law of Thermodynamics4. the Law of Definite Proportions5. the Law of Multiple Proportions6. measuring % of the reacting part of air7. the Law of Mass Action

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The Various Ways You could State the Law of Constant Composition(aka) Law of Definite Proportions• Elements combine in definite mass ratios

to form compounds.• A given chemical compound always

contains the same proportion by mass of its constituent elements.

• The relative mass of each element in a particular compound is always the same, regardless of preparation or source.

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Law of Constant Composition(aka) Law of Definite Proportions

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What is the Law of Multiple Proportions? (from John Dalton)• If two elements form more than one

compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

• for instance; A fixed mass of carbon, say 10.0 grams, may react with 13.3 grams of oxygen to produce one oxide, or with 26.6 grams of oxygen to produce the other.

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What is the Law of Multiple Proportions? (from John Dalton)• The ratio of the masses of oxygen that can react with

10.0 grams of carbon is 26.6 : 13.3 ≈ 2:1, a ratio of small whole numbers.

• Dalton interpreted this result in his atomic theory by proposing (correctly in this case) that the two oxides have one and two oxygen atoms respectively for each carbon atom.

• In modern notation the first is CO (carbon monoxide) and the second is CO2 (carbon dioxide).

• The law of multiple proportions is best demonstrated using simple compounds (as opposed to large hydrocarbons.)

• John Dalton first expressed this observation in 1804 and published it in 1808.

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Nitrogen and Oxygen exhibiting the Law of Multiple Proportions.

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Which of the properties listed below are intensive?Select all that apply.

1. Mass2. Weight3. Temperature4. Volume5. Density

6. Length7. Heat capacity8. Specific heat

capacity9. Melting Point

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Which of the properties listed below are intensive?Select all that apply.




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Physical Properties• An extensive property will change when the

size of the sample changes.✓ Mass, volume, weight, length, and heat

capacity are extensive properties.• An intensive property does not depend on

sample size and is often (though not always) unique to that type of matter (sometimes called a characteristic property).✓ Density, melting point, specific heat capacity,

color, and temperature are intensive properties.

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What property would the instrument shown, be useful for measuring?Select all that apply.




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What property would the instrument shown, be useful for measuring?Select all that apply.




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Which of the following techniques are useful for physical separation of homogenous mixtures?Select all that apply.

1. Distillation2. Mass to mole

conversion3. Combustion4. Filtration

5. Chromatography6. Vector analysis7. Centrifuging8. Neutralization9. Electrolysis

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Which of the following techniques are useful for physical separation of homogenous mixtures?Select all that apply.

1. Distillation2. Mass to mole

conversion3. Combustion4. Filtration

5. Chromatography6. Vector analysis7. Centrifuging8. Neutralization9. Electrolysis

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Distillation - The physical property(ies) of substances that makes distillation an effective separation technique is Select all that apply.

1. melting point2. boiling point3. mass4. solubility5. temperature6. particle size7. polarity8. specific heat capacity9. volume 40

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Distillation - The physical property(ies) of substances that makes distillation an effective separation technique is Select all that apply.• Distillation is generally used to separate two miscible

liquids, not usually a nonvolatile solid dissolved in a liquid.

1. melting point2. boiling point3. mass4. solubility5. temperature• certainly temperature is important in this procedure,

but all materials would be at the same temperature at any given time until running through the condenser.

6. particle size7. polarity• You can argue that these two properties influence

boiling point... but these would not be the primary property causing the separation.

8. specific heat capacity9. volume 41

miscible - the property of liquids to mix in all proportions forming a homogeneous solution.

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Gravity & Vacuum FiltrationBüchner Funnel Set-up for vacuum filtration.

Side-arm flask

Plastic Buchner funnel

Rubber stopper

Perforated platform to hold filter paper (same exact size as platform)

Hose to vacuum pump

Effluent

Filter paper

Gravity filtration with fluted filter paper.

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Filtration - The physical property(ies) of substances that makes filtration an effective separation technique is Select all that apply.1. melting point2. boiling point3. volume4. solubility5. temperature6. particle size7. polarity8. specific heat capacity9. density 43

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Filtration - The physical property(ies) of substances that makes filtration an effective separation technique is Select all that apply.1. melting point2. boiling point3. volume4. solubility• soluble substances will sometimes ionize to smaller particles or at

the very least “unclump” making solubility play a roll.5. temperature6. particle size• ultimately what fits through the holes of the filter and what does not,

depends on particle size.7. polarity8. specific heat capacity9. density

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Paper Chromatography

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Chromatography - The physical property(ies) of substances that makes chromatography an effective separation technique is Select all that apply.

1. melting point2. boiling point3. volume4. solubility5. temperature6. particle size7. polarity8. specific heat capacity9. density 46

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Chromatography - The physical property(ies) of substances that makes chromatography an effective separation technique is Select all that apply.1. melting point2. boiling point3. volume4. solubility• certainly the substances to be separated must be soluble in the mobile

phase for any separation to occur.5. temperature6. particle size7. polarity• the polarity of the molecules to be separated affect their “stickiness” to

each other and to the solvent, affect the rate (and resulting distance) at which they will travel across the stationary phase (aka medium)

8. specific heat capacity9. density 47

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Centrifuging - The physical property(ies) of substances that makes centriguging an effective separation technique is Select all that apply.

1. melting point2. boiling point3. volume4. solubility5. temperature

6. particle size7. polarity8. specific heat

capacity9. density

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Centrifuging - The physical property(ies) of substances that makes centrifuging an effective separation technique is Select all that apply.

1. melting point2. boiling point3. volume4. solubility5. temperature6. particle size• the larger particle size may

play a role

7. polarity8. specific heat capacity9. density• the greater inertia of the more

dense particles make them tend to collect near the outside of the “swing”

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Techniques for Physical Separation• Distillation: Using varied boiling points to remove

the more volatile solvent from solution, leaving the solute.

• Filtration: Using a semi-permeable barrier to block the passage of larger particles (like a strainer).

• Chromatography: Some substances will be “dragged” by a “sticky” solvent faster than others, separating substances as a function of time.

• Centrifuging: A centrifuge is used to rapidly separate dense substances from less dense substances. It can also be used for gases.

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Physical vs Chemical Changes• Physical Changes✓ Appearances and physical properties

may change, but the identities of the chemicals remains the same.

• Chemical Changes✓ Appearances and physical properties are

likely to change because the identity of the substances will change.

✓ New substances will be formed.

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Which reaction below would best represent the electrolysis of water?

1. H2O(L) → H2O(g)2. H2O → H2 + ½O23. H2O → H+ + OH−4. H2O → 2H + O5. H2O → 2H+ + O2−

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Which reaction below would best represent the electrolysis of water?

1. H2O(L) → H2O(g)2. H2O → H2 + ½O23. H2O → H+ + OH−4. H2O → 2H + O5. H2O → 2H+ + O2−

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Chemical Change:

Electrolysisof Water

H2O → H2 + ½O2

Physical Change:Boiling of waterH2O(L) → H2O(g)

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Accuracy & PrecisionSignificant Figures

and more...

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Which dartboard shows good accuracy? Select all that apply.

1 2 3

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Which dartboard shows good accuracy? Select all that apply.

• I suppose you could argue that # 2 was also good accuracy if the game you were playing required you to hit that area of the board. I was going on the assumption that the bulls-eye was the point of the game.

1 2 3

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“Exactness”, Accuracy, and Precision

• “Exactness”✓ The number of decimal

places in the measurement.

• Accuracy✓ How close the value

agrees with the accepted value.

• Precision✓ The reproducibility of the

values.

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Two Kinds of Numbers• Exact numbers

✓ values that are known exactly✓ defined values or quantities counted

‣ 12 eggs = 1 dozen‣ 27 people in the room‣ 2.54 cm per 1 inch (the 1 in this definition is not just 1 sig fig)

• Inexact numbers✓ values with uncertainty✓ measured quantities are always inexact✓ measurements are reported indicating that only the

last digit is uncertain✓ only particular digits in measurements are

significant figures59

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Record the length of the bar shown.

cm1 2

1 2

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The measuring device determines the number of Significant Figures that you must record.

• Since the ruler’s increments are tenths (0.1) you must record the measurement to the hundreth’s place, even if it is a zero.

• Don’t forget the units.✓ Naked numbers are obscene.

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1 2

1 2

0.70 cm

cm

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cm1 2

0.1 0.2

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cm1 2

0.1 0.2

0.100 cm

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cm1 2

0.01 0.02

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cm1 2

0.01 0.02

0.0007 cm or 0.0008 cm

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For the measurement, 0.03050, which choice correctly underlines the significant figures? Select all that apply.1. 0.030502. 0.030503. 0.030504. 0.03050

5. 0.030506. 0.030507. 0.030508. 0.03050

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For the measurement, 0.03050, which choice correctly underlines the significant figures? Select all that apply.1. 0.030502. 0.030503. 0.030504. 0.03050

5. 0.030506. 0.030507. 0.030508. 0.03050

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For the measurement, 80.030, how many significant figures?1. 12. 23. 34. 45. 56. 0

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For the measurement, 80.030, how many significant figures?1. 12. 23. 34. 45. 56. 0

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Just which numbers are significant?A. All nonzero digits are significant.B. Zeros between two significant figures are

themselves significant.C. Those pesky zeros

• Leading zeros at the beginning of a number are never significant.

• Trailing zeros at the end of a number are significant if a decimal point is written in the number.

D. A zero that is not significant is still important.A. 200 is not the same as 2, those zeros are important.B. 0.000034 is not the same as 34, the zeros are important

to show how small the number is.70

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Calculate the mass of liquid in the beaker, and determine the number of significant figures in the result.1. 12. 23. 34. 45. 56. 0

mass of empty beaker (g) 62.287

mass of beaker with alcohol (g) 67.317

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Calculate the mass of liquid in the beaker, and determine the number of significant figures in the result.1. 12. 23. 34. 4 sig figs5. 56. 0

mass of empty beaker (g) 62.287

mass of beaker with alcohol (g) 67.317

mass of alcohol (g) 5.030

When adding or subtracting, the number of significant figures can change.

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Calculate the ∆T, and determine the number of significant figures in the result.1. 12. 23. 34. 45. 0

starting temp (ºC) 17.73

final temp (ºC) 16.93

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Calculate the ∆T, and determine the number of significant figures in the result.1. 12. 2 sig figs3. 34. 45. 0

starting temp (ºC) 17.73

final temp (ºC) 16.93

temp change (ºC) 0.80

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Significant Figures Rules for rounding off when calculating.•Addition and Subtraction

• The answer can have no more decimal places than the measurement with the least amount.

•Multiplication and Division• The answer must be rounded to the same number of sig

figs as the measurement with the least number of sig figs.

• The bottom line in AP: If you round to within +/- 1 sig fig of what it should be, you will not likely lose (much) credit. Only if you completely ignore any rounding, or if you round too much.

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Metric Units

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SI units - Système International d’Unités• Seven base units from which all other

units are derived:✓ Mass, kilogram, kg✓ Length, meter, m✓ Time, second, s (or sec)✓ Temperature, Kelvin, K✓ Amount of substance, mole, mol !!✓ Electric current, ampere, A✓ Luminous intensity, candela, cd

• What seems to be missing?

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Volume is a Derived Unit• Volume is • L x W x H

✓ = length3

• A m3 is too large of a unit to be useful, so we use the dm3 or the cm3.

• You should remember that by definition:✓ 1 dm3 = 1 L✓ 1 cm3 = 1 ml

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Volume Measuring Devices

What’s seems to be missing?

The accuracy required, would determine which device you should use.

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the Beaker & the Erlenmeyer Flask• Remember, both are volume holding

devices, but not accurate volume measuring devices

• It is only useful for very approximate measurements.

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Select the metric conversion that is correct for 37.0 mSelect all that apply.

1. 370 dm (deci = d, we will never use deka = da)2. 0.0037 km (kilo)3. 3.70 x 10-3 mm (milli)4. 3.7 x 10-8 nm (nano)5. 3700 cm (centi)6. 3.70 x 10-5 µm (micro)

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Select the metric conversion that is correct for 37.0 m Select all that apply.1. 370 dm

• should be 3.70x102 dm to show sig figs2. 0.0037 km

• should be 0.00370 km to show sig figs3. 3.70 x 10-3 mm

• should be 3.70x104 mm (mm = milli- not micro, µ)4. 3.7 x 10-8 nm

• should be 3.70x10-8 nm to show sig figs5. 3700 cm

• should be 3.70x103 mm to show sig figs6. 3.70 x 10-5 µm (106 µm (micrometer) = 1 m)

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Metric Magnitudes• Prefixes used to ∆ the standard units to

express measurements that are very large or very small. Common prefixes you should know include:

• kilo – (k) x103 (x 1,000)• deci – (d) x10-1

• centi – (c) x10-2 • milli – (m) x10-3 • micro – (μ) x10-6

• nano – (n) x10-9

× 110

⎛⎝⎜

⎞⎠⎟

× 1100

⎛⎝⎜

⎞⎠⎟

× 11000

⎛⎝⎜

⎞⎠⎟ or ×

1103

⎛⎝⎜

⎞⎠⎟

× 11,000,000

⎛⎝⎜

⎞⎠⎟or × 1

106⎛⎝⎜

⎞⎠⎟

× 11,000,000,000

⎛⎝⎜

⎞⎠⎟or × 1

109⎛⎝⎜

⎞⎠⎟

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Select the conversions that are correct. Select all that apply.1. 25ºC = 273 K2. 98ºF ≃ 100ºC

3. −10ºC = 283 K4. 200 K = −73ºC5. 0 K < −273ºF6. −40ºF = −40ºC

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Three Temperature Scales

absolute zero0 K-273.15ºC-459.7ºC

Do we need to revote?85

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Select the conversions that are correct. Select all that apply.1. 25ºC = 273 K

• 25ºC = 298 K2. 98ºF ≃ 100ºC

• 98ºF ≃ 37ºC3. −10ºC = 283 K

• −10ºC = 263 K4. 200 K = −73ºC5. 0 K < −273ºF6. −40ºF = −40ºC

• So you must know that ºC + 273 = K

• alternatively: K − 273 = ºC

• You do NOT need to know the Celsius to Fahrenheit conversion.ºF = ⁹/₅ºC + 32ºC = ⁵/₉(ºF − 32)

You don’t really need to know this, it’s just an interesting tidbit of info.

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The normal boiling point of liquid nitrogen is 77 K. At −200ºC, nitrogen will be Select all that apply.

1. solid2. liquid3. gas4. not enough information

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The normal boiling point of liquid nitrogen is 77 K. At -200ºC, nitrogen will be Select all that apply.

1. solid2. liquid3. gas liquid nitrogen will boil at -196ºC

at 1 atmosphere of pressure.4. not enough information

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The density of platinum is 21.45 g/ml. Calculate the volume of a piece of Pt that has a mass of 124.36 g1. 0.17 ml2. 0.172 ml3. 0.1725 ml4. 0.17248 ml

5. 5.80 ml6. 5.798 ml7. 5.7977 ml8. 5.797669 ml

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The density of platinum is 21.45 g/ml. Calculate the volume of a piece of Pt that has a mass of 124.36 g1. 0.17 ml2. 0.172 ml3. 0.1725 ml4. 0.17248 ml5. 5.80 ml6. 5.798 ml (4 SF)

7. 5.7977 ml8. 5.797669 ml

Md = V

How are you at solving literal equations?

Md = V

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Which pair best represents two 25 g cylinders, one aluminum and one copper?

CuAl AlCu Al Cu

Pair 1 Pair 2 Pair 3

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Which pair best represents two 25 g cylinders, one copper and one lead?

• Aluminum is less dense than copper, thus the same mass corresponds to more volume than for the more dense copper.

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CuAl Al Cu

Pair 1

AlCu

Pair 2 Pair 3

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As the temperature of a solution increases the molarity of a solution will1. increase2. decrease3. stay the same4. impossible to predict

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As the temperature of a solution increases the molarity of a solution will1. increase2. decrease

• Vol of any solution will increase as the temperature increases. The number of moles, like mass will not change, thus an increasing denominator will cause a decrease in the Molarity.

3. stay the same4. impossible to predict 94

molesMolarity, M =V (L)

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Examine the blocks attached to the balance. Based on their positions and sizes, which block is more dense?1. blue block2. red block3. impossible to

predict

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Examine the blocks attached to the balance. Based on their positions and sizes, which block is more dense?1. blue block

• Since the blue block is smaller in size, yet more mass, it must be more dense

2. red block3. impossible to predict

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predict

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Examine the blocks attached to the balance. Based on their positions and sizes, which block is more dense?1. blue block2. red block

• Since the red block is smaller in size, yet more mass, it must be more dense

3. impossible to predict98

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predict

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Examine the blocks attached to the balance. Based on their positions and sizes, which block is more dense?1. blue block2. red block3. impossible to predict

• The dark block with more mass does not give us definitive information. The dark block might be the same, or more, or less dense than the lighter colored 100

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Scientific Method

not so likely to show up on the AP Exam

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The Scientific MethodScience is not a linear set of steps. It’s a messy process that can take many different paths.• Observation: What you see without interpretation.• Question: Create a question from your observations or ideas.• Hypothesis: Often a question. A reasonable explanation of

your observations. A possible answer to your question. This is NOT a random guess. Most importantly, it must be testable.

• Experiment/Test: A controlled observation (a test of your hypothesis).

• Collect and Analyze Data: Experimental results must be collected and interpreted. A valid experiment must be reproducible.

• Conclusions: Data is explained and compared to the hypothesis. The final step… What next? How can I use this new information?

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Theory vs. Law• A theory is an explanation of observations of

natural phenomena. A theory cannot be proved, only disproved.

• If a theory is disproved, it must be modified or rejected.

• A theory explains why things do what they do.• A law is a description of observations and

experiences. A law describes what will happen. Because a law is a general description of observations.

• A law states what happens, and allows us to predict outcomes of future events.

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Doing science is messy.1. Make an observation2. Propose an explanation3. Do an experiment4. Repeat - after enough of this

you might make:a) A law - summary ORb) A theory - explanation

5. Of course no law or theory is above scrutiny, so further experiments should be continued to confirm the validity of the law or theory.

4. Repeat

5. Repeat

1.

2.

3.

a)b)

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Hypothesis - Law - Theory• Hypothesis✓ Testable explanation for an observation

• Law✓ Summary statement of many observations

• Theory✓ An explanation of many observations

A Law tells us what happens.A theory tells us why it happens.

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Law and Theory• Don’t think that a Law is a Theory that

has been proven.• Don’t think that a Law is any more exact

than a Theory.• Don’t think that a Theory is a proven

Hypothesis.• Don’t think that a Law is “proven” and a

Theory is not “proven”.Law is what. Theory is why.

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Two Words to Avoid: true & prove• Avoid using the words prove and truth.• The methods of science never prove anything.

✓ The word "proof" refers to a strictly mathematical process.

• Science doesn’t claim absolute truths. Avoid the word "truth" in scientific discussion.

• An experiment may disprove a Law, but no finite number of experiments ever establish a Law as absolutely true.

• In a single experiment you might "verify" or "confirm" the validity of a Law, but not actually prove it.

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Unit A: Introduction: Matter and Measurement · 2018. 10. 15. · Gravity & Vacuum Filtration...

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Transcript of Unit A: Introduction: Matter and Measurement · 2018. 10. 15. · Gravity & Vacuum Filtration...