Professor Abdul Muttaleb JaberProfessor Abdul Muttaleb Jaber

Chemistry DepartmentChemistry Department

Office: Room # 261FOffice: Room # 261F

Tel: 2611Tel: 2611

E-mail: E-mail: amjaber@kfupm.edu.sa

Office hours: Office hours: S 9-11 amS 9-11 am

U 10-11 amU 10-11 am

M 9-11amM 9-11am

Chapter 1Chapter 1Chemical FoundationsChemical Foundations

An overviewAn overviewThe scientific methodThe scientific methodUnits of measurementsUnits of measurementsUncertainty in measurementsUncertainty in measurementsSignificant figures and Significant figures and calculationscalculationsDimensional analysisDimensional analysisTemperatureTemperatureDensityDensityClassification of matterClassification of matter

1.11.1 Chemistry: an overviewChemistry: an overview

MatterMatter is composed of is composed of atomsatomsAtoms are found as Atoms are found as individuals or individuals or moleculesmoleculesAtoms and molecules are connected by Atoms and molecules are connected by electronselectronsThe challenge of chemistry is to think The challenge of chemistry is to think of the of the material the the atomic levelatomic level100 different types of atoms form all 100 different types of atoms form all substances in the worldsubstances in the world

Matter is composed of various types of Matter is composed of various types of atoms or molecules.atoms or molecules.

Water is composed of O and H; Water is composed of O and H; HH22OO

An electric spark causes a mixture of OAn electric spark causes a mixture of O22

and Hand H2 2 to explode forming Hto explode forming H22O. O.

One substance changes to another byOne substance changes to another by

reorganizing the way atoms attached to reorganizing the way atoms attached to each othereach other

Scientific methodScientific method It is a way of solving problemsIt is a way of solving problems

It consists of the following steps:It consists of the following steps:– Observation-- what is seen or measured what is seen or measured– Hypothesis-- guess of why things behave the way guess of why things behave the way

they do. (possible explanation for an observation)they do. (possible explanation for an observation)– ExperimentExperiment- designed to test hypothesis- designed to test hypothesis

These steps would lead to new observations, and the cycle These steps would lead to new observations, and the cycle goes ongoes on

Once a set of hypotheses agree withOnce a set of hypotheses agree with

observations, they are grouped into a observations, they are grouped into a theorytheory

Scientific methodScientific method

TheryThery is a set of tested hypothesis is a set of tested hypothesis that gives an overall explanation for that gives an overall explanation for a natural phenomenona natural phenomenonLawsLaws are summaries of observations are summaries of observations

Often mathematical relationshipOften mathematical relationship

1.31.3 Units of measurementsUnits of measurements

Every measurement has two partsEvery measurement has two parts

NumberNumber

Scale (called a unit)Scale (called a unit)

SI system (SI system (le Systeme Internationalle Systeme International in in French) based on the metric systemFrench) based on the metric system

Examples:Examples:2020 grams grams20 k g = 20 k g = 20 X1020 X1033 gg20 m g = 20 m g = 20 X1020 X10-3-3 gg6.63 6.63 Joule seconds Joule seconds

Prefix

Metric SystemMetric System

Fundamental SI Fundamental SI base Unitsbase Units

Mass - kilogram (kg)Mass - kilogram (kg)

Length- meter (m)Length- meter (m)

Time - second (s)Time - second (s)

Temperature- Kelvin (K)Temperature- Kelvin (K)

Electric current- ampere (amp, A)Electric current- ampere (amp, A)

Amount of substance- mole (mol)Amount of substance- mole (mol)

Prefixes used in SI unitsPrefixes used in SI units

giga- giga- GG 1,000,000,0001,000,000,000 101099

mega - mega - MM 1,000,0001,000,000 101066

kilo - kilo - kk 1,0001,000 101033

deci-deci- dd 0.10.1 10 10-1-1

centi-centi- cc 0.010.01 10 10-2-2

milli-milli- mm 0.0010.001 10 10-3-3

micro-micro- 0.0000010.000001 10 10-6-6

nano-nano- nn 0.0000000010.000000001 10 10-9-9

Volume measurement: LiterVolume measurement: Liter

Liter is defined as the volume of 1 Liter is defined as the volume of 1 dmdm33

–11 dm dm33 = =

– (10cm)(10cm)33 = =

– 1000 cm1000 cm33 = =

– 1000mL1000mL

GraduatedCylinder

Pipet Buret

Volumetric Flask

Mass and WeightMass and Weight

MassMass is measure of resistance to is measure of resistance to change in motion change in motion

WeightWeight is force of gravity. is force of gravity.

Sometimes used interchangeablySometimes used interchangeably

Mass can’t change, weight canMass can’t change, weight can

Electronic Electronic AnalyticalAnalyticalBalanceBalance

All scientific measurements are subject to All scientific measurements are subject to error.error.

These errors are reflected in the These errors are reflected in the observation that observation that two successive two successive measurementsmeasurements of the same quantity are of the same quantity are different.different.

Errors in MeasurementErrors in Measurement

Types of ErrorsTypes of Errors

Random Random Error Error ((IndeterminateIndeterminate Error) - Error) - measurement has an equal probability of measurement has an equal probability of being high or low.being high or low.

SystematicSystematic Error Error ((DeterminateDeterminate Error) - Occurs Error) - Occurs in the in the same directionsame direction each time (high or low), each time (high or low), often resulting often resulting from poor technique of from poor technique of measurement or bad equipmentmeasurement or bad equipment..

You can have precision without accuracyYou can have precision without accuracy

You can’t have accuracy without precision You can’t have accuracy without precision (unless you’re really lucky).(unless you’re really lucky).

Uncertainty in Measurements

Uncertainty in MeasurementUncertainty in Measurement A A measurementmeasurement always has always has

some degree of uncertainty.some degree of uncertainty. Uncertainty has to be indicated in any Uncertainty has to be indicated in any measurement.measurement. Any measurement has Any measurement has certain digits and certain digits and one uncertain digit. one uncertain digit. A digit that must be A digit that must be estimatedestimated is is

called called uncertain.uncertain. The number of certain digits + the The number of certain digits + the uncertain digit is called number of uncertain digit is called number of significant figures.significant figures.

Precision and AccuracyPrecision and Accuracy

Accuracy:Accuracy: Agreement of a particular Agreement of a particular value to the true value (degree of value to the true value (degree of correctness)correctness)– Measurements that are close to the Measurements that are close to the

“correct” value are “correct” value are accurateaccurate..Precision:Precision: The degree of agreement The degree of agreement among several measurements of the among several measurements of the same quantity (degree of same quantity (degree of repeatability).repeatability).– Measurements that are close to Measurements that are close to

each other are each other are preciseprecise..

Precision and AccuracyPrecision and Accuracy

•The number of digits reported in a measurement reflect the accuracy of the measurement and the precision of the measuring device.

# Sig figs. =?

•All the figures known with certainty plus one extra figure are called significant figures.

1.5 Significant figures and calculations

# Sig figs. =?

• For multiplication and divisionFor multiplication and division• the results are reported to the least number of significant

figures

354.760 X 0.0004567 = 0.162018892

= 0.1620• For addition and subtraction• The results are reported to the least number of decimal places

345.672 – 34.56720 = 311.1048345.672 – 34.56720 = 311.1048

= = 311.105311.105

Significant figures in computation

Rules for Counting Significant Figures

Nonzero integers always count as significant figures.

3456 has

4 sig figs.

ZerosLeading zeros do not count as significant figures. (Zeros before the nonzero digit)

0.0486 has3 sig figs.0.0003 hasone significant figure

Captive zeros always count as significant figures.always count as significant figures.

16.07 has16.07 has

4 sig figs.4 sig figs.

ZerosTrailing zeros are significant only

if the number contains a decimal point.

9.300 has

4 sig figs.

Exact numbers have an infinite number of significant figures.

1 inch = 2.54 cm, exactly

• Zeros at the end of a number before a

decimal place are ambiguous

10,300 g has: 3 or 4 or 5??

Scientific Notation

•Addition and Subtraction

(6.6 x 10-8) + (4.0 x 10-9) =

(3.42 x 10-5) – (2.5 x 10-6) =

7 x 10-8

3.17 x 10-5

(Note that these answers have been expressed in standard form)

13

Rules for Rounding Off

To get the correct number of significant digits

you need to round numbers

In a series of calculations get one extra digit then

round

If the digit to be removedis less than 5, the preceding digit stays the same

is equal to or greater than 5, the preceding digit is increased by 1

Don’t forget to add place-holding zeros if necessary to keep value the same!!

Multiple computations

2.54 X 0.0028 = 0.0105 X 0.060

1) 11.3 2) 11 3) 0.041

Continuous calculator operation =

2.54 x 0.0028 0.0105 0.060

Here, the mathematical operation requires Here, the mathematical operation requires that we apply the addition/ subtraction rule that we apply the addition/ subtraction rule first, then apply the multiplication/division first, then apply the multiplication/division rule.rule.

=12

1.61.6 Dimensional AnalysisDimensional Analysis

Using the units to solve Using the units to solve problemsproblems

Method of calculation utilizing a knowledge of Method of calculation utilizing a knowledge of units.units.

Conversion factors are used to manipulate units:Conversion factors are used to manipulate units:

The conversion factors are simple ratios:The conversion factors are simple ratios:

Dimensional AnalysisDimensional Analysis

m

cm 100 ;

cm 100

m : cm tom of Conversion

How many minutes are in 2.5 hoursHow many minutes are in 2.5 hours??

Initial unitInitial unit

2.5 hr2.5 hr

ConversionConversion Final Final

factorfactor unitunit

2.5 hr x 2.5 hr x 60 min 60 min = 150 = 150 min min

1 hr1 hr

How many seconds are in 1.4 days?How many seconds are in 1.4 days?

Unit planUnit plan: days hr min seconds: days hr min seconds

1.4 days x 1.4 days x 24 hr24 hr x x ????

1 day1 day

1.4 day x 24 hr x 60 min x 60 sec

1 day 1 hr 1 min

= 1.2 x 105 sec

Exact numbers

Multiple unitsMultiple unitsThe speed limit is 65 mi/hr. What is The speed limit is 65 mi/hr. What is this in m/s?this in m/s?– 1 mile = 1760 yds1 mile = 1760 yds– 1 meter = 1.094 yds1 meter = 1.094 yds

65 mihr

1760 yd1 mi 1.094 yd

1 m 1 hr60 min

1 min60 s

InitialInitial

8450 ft x 8450 ft x 12 in. 12 in. x x 2.54 cm 2.54 cm x x 1 m 1 m

1 ft1 ft 1 in. 1 in. 100 cm 100 cm

x x 1 min 1 min x x 60 sec 60 sec = 2400 sec = 2400 sec

65 m65 m 1 min 1 min

If you are running at a speed of 65 meters per If you are running at a speed of 65 meters per minute, how many seconds will it take for you to minute, how many seconds will it take for you to walk a distance of 8450 feet?walk a distance of 8450 feet?

Units to a PowerUnits to a Power

How many mHow many m3 3 is 1500 cmis 1500 cm33??

1500 cm33 1 m100 cm

33

1.7 Temperature 1.7 Temperature

Define the three temperature scales: Define the three temperature scales: Celsius , Fahrenheit and Kelvin Celsius , Fahrenheit and Kelvin

Perform conversion from one to Perform conversion from one to another. another.

Units of Temperature between Units of Temperature between Boiling and FreezingBoiling and Freezing

FahrenheitFahrenheit Celsius Celsius KelvinKelvin

Water boils 212°F 100°CWater boils 212°F 100°C 373 K 373 K

180°180° 100°C 100K 100°C 100K

Water freezes 32°F 0°CWater freezes 32°F 0°C 273 K 273 K

K = K = ooC + 273C + 273

32-F95

C

32C59

F

1.8 Density1.8 Density

DensityDensity is the mass of substance is the mass of substance

per unit volume of the substance:per unit volume of the substance:

density = mass

volume

Densities of Various Common Substances* at 20° CDensities of Various Common Substances* at 20° C

Density ProblemDensity ProblemAn empty container weighs 121.3 g. When filled with a An empty container weighs 121.3 g. When filled with a liquid (density 1.53 g/cmliquid (density 1.53 g/cm33 ) the container weighs 283.2 g. ) the container weighs 283.2 g. What is the volume of the container?What is the volume of the container?

g 161.9 liquid theof Mass

gV 9.1613

3

10653.1

19.161 cm

g

cmgV

1.9 Classification of Matter1.9 Classification of Matter

Matter:Matter: Anything occupying space and having Anything occupying space and having mass.mass.

Three States of MatterThree States of Matter::

Solid: Solid: rigid - fixed volume and shaperigid - fixed volume and shape

Liquid: Liquid: definite volume but assumes the definite volume but assumes the shape of its containershape of its container

Gas: Gas: no fixed volume or shape - assumes no fixed volume or shape - assumes the shape of its containerthe shape of its container

Types of MixturesTypes of Mixtures Matter could be pure (one component only) or Matter could be pure (one component only) or mixturemixture Mixtures have variable composition (more than Mixtures have variable composition (more than one component)one component)

AA homogeneous mixture homogeneous mixture has visibly has visibly indistinguishable indistinguishable components usually called a components usually called a solution (for example, tap water)solution (for example, tap water)

AA heterogeneous mixture heterogeneous mixture has visibly has visibly distinguishabledistinguishable components, clearly not uniform components, clearly not uniform (for example milk)(for example milk)

Organization of MatterOrganization of Matter

A physical change, is associated with a A physical change, is associated with a change in the physical appearance but change in the physical appearance but not in chemical compositionnot in chemical composition– Ice melts: a solid is converted into a liquid.Ice melts: a solid is converted into a liquid.

When a substance changes its chemical When a substance changes its chemical composition, it undergoes a chemical composition, it undergoes a chemical change:change:

– HH22 + O + O22 pure water. pure water.

– In the flask containing water, there is no In the flask containing water, there is no oxygen or hydrogen left over.oxygen or hydrogen left over.

Physical and Chemical ChangesPhysical and Chemical Changes

Physical and Chemical Changes

Properties of Matter

Mixtures can be separated if their Mixtures can be separated if their physical physical properties are different.properties are different.

Solids can be separated from liquids by Solids can be separated from liquids by means of means of filtrationfiltration..

The solid is collected in filter paper, and The solid is collected in filter paper, and the solution, called the filtrate, passes the solution, called the filtrate, passes through the filter paper and is collected in through the filter paper and is collected in a flask.a flask.

Separation of MixturesSeparation of Mixtures

FiltrationFiltration

Homogeneous liquid mixtures can be Homogeneous liquid mixtures can be separated by separated by distillationdistillation..

Distillation requires the different liquids to Distillation requires the different liquids to have different boiling points.have different boiling points.

Thus, each component of the mixture is Thus, each component of the mixture is boiled and collected.boiled and collected.

The lowest boiling fraction is collected The lowest boiling fraction is collected first.first.

Separation of MixturesSeparation of Mixtures

DistillationDistillation

Distillation is a physical change: No chemical Distillation is a physical change: No chemical change occurs when salt water is distilled.change occurs when salt water is distilled.

ChromatographyChromatography can be used to separate can be used to separate mixtures that have different abilities to mixtures that have different abilities to adhere to solid surfaces.adhere to solid surfaces.

The greater the affinity the component The greater the affinity the component has for the surface (paper) the slower it has for the surface (paper) the slower it moves.moves.

The greater affinity the component has The greater affinity the component has for the liquid, the faster it moves.for the liquid, the faster it moves.

Chromatography can be used to separate Chromatography can be used to separate the different colors of inks in a pen.the different colors of inks in a pen.

Separation of MixturesSeparation of Mixtures

Paper chromatographyPaper chromatography: : A Line of the mixture to A Line of the mixture to be separated is placed at be separated is placed at one end of a sheetone end of a sheet

The Paper Acts The Paper Acts as a Wick to as a Wick to Draw up the Draw up the LiquidLiquid

Component with Component with the weakest the weakest attraction for the attraction for the paper travels paper travels

fasterfaster

Compounds and elementsCompounds and elements

Element:Element: A substance that cannot be A substance that cannot be decomposed into simpler substances by decomposed into simpler substances by chemical means.chemical means.

Compound:Compound: A substance with a A substance with a constant composition that can be constant composition that can be broken down into elements by broken down into elements by chemical processes.chemical processes.