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General ChemistryIntroduction: Definitions and Measurements

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*Aspartame NutraSweet. 5 times sweeter than sugar.

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Chemistry is the study of matter, its properties,

as well as its transformations and energyassociated with those transformations.

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Chemistry: A Definition

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Nobody fully knows what it really is. Heres asmuch as we could surmise:

Matter is the stuff around us

The stuff is made of molecules and atoms

Structure of Matter

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Individual Substances,or Compounds:

identical molecules

well-defined set of physical and chemical

properties

Mixtures :

different molecules and other particles

physical and other

properties depend on relative amounts of substances in them

Composition of Matter

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SOLIDfixed volumefixed shape

LIQUIDfixed volume

changing shape

GASchanging volumechanging shape

solid salt crystal

Na Cl liquid watermolecules

molecules of a gas

Three States of Matter

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Examples of physicalproperties:

Melting pointBoiling pointDensityPlasticity

ConductivityColor

Examples of chemicalproperties:

CorrosivenessFlammabilityOther types of

reactivity

Properties: physical and chemical

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extensive : depend on the amount of substance presentintensive : independent of the amount of substance present

Examples of physical properties and parameters:

Mass, volume - extensiveMelting point - intensiveBoiling point - intensiveDensity

PlasticityConductivityColor

Physical properties

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extensive : depend on the amount of substance presentintensive : independent of the amount of substance present

Examples of physical properties and parameters:

Mass, volume - extensiveMelting point - intensiveBoiling point - intensiveDensity - intensive

Plasticity - intensiveConductivity - intensiveColor - intensive

Physical properties

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physical properties:

Color: bluish pale grey metallicMelting point: 419.53 oC [787.15 oF]

Boiling point: 907 oC [1665 oF]Density: 7140 kg/m 3

Resistivity: 5.9 .10 -8 W m

some chemical properties:

tarnishes in the air very slowly dissolves in dilute acid

reacts violently with sulfur (picture above)

Properties: example

Zinc

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Physics: Potential Energyposition of an object

Kinetic Energymotion of an object

Chemistry :Chemical potential energy:

energy stored in the molecules and is determinedby their structure (example: fossil fuels).

Energy: chemical potential energy

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Dawn of humanity: Trial and Error

Modern Science: Observation ! Hypothesis ! Experiment ! Theory

(educated trial/error)

A little bit about the scientific method

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Year 1960, International System of Units, SI units

Measurements

SI Fundamental Units of Measurement

Physical Quantity (Dimension) Unit Name Abbreviation

Mass kilogram kg

Length meter m

Time second s

Temperature kelvin K

Electric Current ampere A

Amount of substance mole mol

Luminous intensity candela cd

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LengthSI: 1 meter (m) = 1.094 yard

1 cm = 10 -2 m = 0.3937 in1 inch = 2.54 cm

VolumeSI: 1 m 3

1 L (liter) = 10 -3 m 3 = 1 dm 31 mL = 1 cm 3 = 10 -3 L = 10 -3 dm 3

1 L = 1.057 quart1 fluid ounce = 29.57 mL

Measurements Useful in Chemistry

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The volume of an irregularly shaped solid can bedetermined by the volume of water it displaces.

Volume: Practice Exercise

Volume (mL) = volume after - volume before =21.5 mL - 23.0 mL = 1.5 mL (cm 3)

Volume (fl. oz.) =

1 fl. oz = 29.57 mL

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The volume of an irregularly shaped solid can bedetermined by the volume of water it displaces.

Volume: Practice Exercise

Volume (mL) = volume after - volume before =21.5 mL - 23.0 mL = 1.5 mL (cm 3)

Volume (fl. oz.) =

1 fl. oz = 29.57 mL 129.57

fl. oz = 1 mL

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The volume of an irregularly shaped solid can bedetermined by the volume of water it displaces.

Volume: Practice Exercise

Volume (mL) = volume after - volume before =21.5 mL - 23.0 mL = 1.5 mL (cm 3)

Volume (fl. oz.) = 1.5 mL " = 0.05 fl oz1 fl oz29.57 ml

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Measurements Useful in Chemistry

MassSI: 1 kilogram (kg) = 2.205 lb

1 gram (g) = 10 -3 kg

Density (d ) !SI: 1 kg/m 3 = g/cm 3 = g/mL

density = massvolume

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Measurements Useful in Chemistry

Temperature

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Measurements Useful in Chemistry

Temperature

T C = ( T F - 32) 59

T F = T C + 32 95

T C = T K + 273

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Temperature: Practice Exercise

The highest daytime temperature recorded on Mars is 27 C,while the average night time temperature is about -107 C.Whats the temperature in Fahrenheit, is it comfortable for humans?

95T F = T C + 32

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Temperature: Practice Exercise

T F = " 27C + 32 = 81 F95Daytime:

The highest daytime temperature recorded on Mars is 27 C,while the average night time temperature is about -107 C.Whats the temperature in Fahrenheit, is it comfortable for humans?

95T F = T C + 32

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Temperature: Practice Exercise

T F = " 27C + 32 = 81 F95

T F = " (-107C) + 32 = -161 F95

Daytime:

Night time:

The highest daytime temperature recorded on Mars is 27 C,while the average night time temperature is about -107 C.Whats the temperature in Fahrenheit, is it comfortable for humans?

95T F = T C + 32

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Time

SI standard unit: second (s)

1 hour = 60 min1 min = 60 s

Measurements Useful in Chemistry

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All devices have limited sensitivity ! uncertainty in measurement

2.84 0.01 g; 82740 5 years

we always estimate the rightmost digit

significant figures: all figures we record in measurement2.84 g; 82740 years

Significant Figures/Uncertainty in

Measurement

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0.0009039 m 9.1 " 10 -5 s 400 L 400. L 400.0 L

Which Figures Are Significant?

! all non-zero digits are significant

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0.0009039 m 9.1 " 10 -5 s 400 L 400. L 400.0 L

4 sf

Which Figures Are Significant?

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0.0009039 m 9.1 " 10 -5 s 400 L 400. L 400.0 L

4 sf 2 sf

Which Figures Are Significant?

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0.0009039 m 9.1 " 10 -5 s 400 L 400 . L 400 .0 L

4 sf 2 sf 1 sf

Which Figures Are Significant?

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0.0009039 m 9.1 " 10 -5 s 400 L 400. L 400.0 L

4 sf 2 sf 1 sf 3 sf

Which Figures Are Significant?

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0.0009039 m 9.1 " 10 -5 s 400 L 400. L 400.0 L

4 sf 2 sf 1 sf 3 sf 4 sf

Which Figures Are Significant?

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1. multiplication and division: the answer has the samenumber of sf as the measurement with the fewest sf :

Volume (cm 3) = 1.23542 cm " 1.0365 cm " 3 cm = 4 cm 3

2. addition and subtraction: the answer has the samenumber of decimal places as the measurement with thefewest number of decimal places.

Volume (mL) = 34.1 ml + 4.943567238956 mL = 39.0 mL

Some Math

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Properties: physical/chemical

States of matter: volume/shape

SI standard units of measurement

Measurements: significant figures/uncertainty

Chapter 1: Overview

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Chapter 1: Overview

massvolumedensity =

T C = ( T F - 32)

T F = T C + 32 95

59

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Practice ExercisesAccording to the ancient greek legend, Archimedes discovered thedisplacement method of density determination while bathing andused it to find the composition of the kings crown. If a crownweighing 4 lb 13 oz displaces 186 mL of water, is it made of pure

gold ( d = 19.2 g/cm 3)?

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Practice Exercises

massvolumedensity = 1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g

According to the ancient greek legend, Archimedes discovered thedisplacement method of density determination while bathing andused it to find the composition of the kings crown. If a crownweighing 4 lb 13 oz displaces 186 mL of water, is it made of pure

gold ( d = 19.2 g/cm 3)?

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Practice Exercises

massvolumedensity = 1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g

mass = 4 lb " 1000 g

2.205 lb+ 13 " 28.3 g/oz = 2182 g

(1814.1 g) (367.9 g)

According to the ancient greek legend, Archimedes discovered thedisplacement method of density determination while bathing andused it to find the composition of the kings crown. If a crownweighing 4 lb 13 oz displaces 186 mL of water, is it made of pure

gold ( d = 19.2 g/cm 3)?

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Practice ExercisesAccording to the ancient greek legend, Archimedes discovered thedisplacement method of density determination while bathing andused it to find the composition of the kings crown. If a crownweighing 4 lb 13 oz displaces 186 mL of water, is it made of pure

gold ( d = 19.2 g/cm 3)? massvolumedensity = 1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g

mass = 4 lb " 1000 g

2.205 lb+ 13 " 28.3 g/oz = 2182 g

d = 2182 g/186 mL = 11.7 g/mL = 11.7 g/cm 3

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Practice Exercises

massvolumedensity =

Copper coins actually contain very little copper. If a coin is97.3% zinc (d = 7.14 g/cm 3) and 2.7% copper (d = 8.95 g/cm 3) bymass, what is its density?

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Practice Exercises

massvolumedensity =

Copper coins actually contain very little copper. If a coin is97.3% zinc (d = 7.14 g/cm 3) and 2.7% copper (d = 8.95 g/cm 3) bymass , what is its density?

mass (Cu) + mass (Zn)volume (Cu) + volume (Zn)=

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Practice Exercises

massvolumedensity =

Copper coins actually contain very little copper. If a coin is97.3% zinc (d = 7.14 g/cm 3) and 2.7% copper (d = 8.95 g/cm 3) bymass , what is its density?

mass (Cu) + mass (Zn)volume (Cu) + volume (Zn)=

Volume (Zn) = 0.973 g7.14 g/cm 3

= 0.136 cm 3

Volume (Cu) = 0.027 g8.95 g/cm 3 = 0.003 cm 3

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Practice Exercises

massvolumedensity =

Copper coins actually contain very little copper. If a coin is97.3% zinc (d = 7.14 g/cm 3) and 2.7% copper (d = 8.95 g/cm 3) bymass , what is its density?

mass (Cu) + mass (Zn)volume (Cu) + volume (Zn)=

Volume (Zn) = 0.973 g7.14 g/cm 3

= 0.136 cm 3

Volume (Cu) = 0.027 g8.95 g/cm 3 = 0.003 cm 3

density = 1.000 g0.139 cm 3 = 7.19 g/cm3