matter and measurement chapter 1. the scientific method 1. observations – something that is...

Matter and Matter and MeasurementMeasurement

Chapter 1Chapter 1

The Scientific MethodThe Scientific Method1.1. Observations – something that is Observations – something that is

witnessed and can be recordedwitnessed and can be recorded QualitativeQualitative QuantitativeQuantitative

2.2. HypothesisHypothesis3.3. ExperimentExperiment4.4. TheoryTheory

1. Tested hypotheses that explains WHY nature behaves in a certain way

2. Change as more info become available

Is the method used to determine the Is the method used to determine the Kentucky Derby winner a qualitative Kentucky Derby winner a qualitative measurement or a quantitative measurement or a quantitative measurement? Explain.measurement? Explain.

Classification of MatterClassification of MatterMatterMatter – anything that takes up – anything that takes up

space and has massspace and has mass

1.1. SolidsSolids

2.2. LiquidsLiquids

3.3. GasesGases

What can you tell me about the What can you tell me about the shape, volume, and shape, volume, and

compressabilty of the above?compressabilty of the above?

MixturesMixtures – matter of variable – matter of variable compositioncomposition

HomogeneousHomogeneous:: Uniform in composition; having Uniform in composition; having

visibly indistinguishable partsvisibly indistinguishable parts HeterogeneousHeterogeneous:: Not uniform in composition; Not uniform in composition;

visually distinguishable partsvisually distinguishable parts

Pure SubstancesPure Substances Elements:Elements:cannot be decomposed into cannot be decomposed into

simpler substancessimpler substances Compounds:Compounds:Two or more elements interacting Two or more elements interacting

with one anotherwith one another Law of Definite proportionsLaw of Definite proportions::The elemental composition of a The elemental composition of a

pure compound is always the pure compound is always the samesame

Properties of MatterProperties of MatterPhysical PropertiesPhysical Properties

1.1. Measured without changing the Measured without changing the identity and composition of identity and composition of substancesubstance

2.2. Includes color, odor, density, Includes color, odor, density, melting/boiling point, and hardnessmelting/boiling point, and hardness

Chemical PropertiesChemical Properties

1.1. Describes the way a substance may Describes the way a substance may change or change or reactreact to form other to form other substancessubstances

Intensive PropertiesIntensive Properties

1.1. Doesn’t depend on the amount Doesn’t depend on the amount in a samplein a sample

2.2. Used to identify substancesUsed to identify substances

3.3. Ex: temperature, melting point, Ex: temperature, melting point, density…density…

Extensive PropertiesExtensive Properties

1.1. Depends on the quantity of the Depends on the quantity of the samplesample

2.2. Ex: mass, volume …Ex: mass, volume …

Scientific NotationScientific Notation•Also known as exponential notationexponential notation

•Way to write very small and very large numbers using powers of ten.

•Answers in Sci. Notation should have ONLY 1 # (1-9) to the left of the decimal

3.6 x 104 = 36 000 5.8 x 10-3 = 0.0058

Why would that be useful?

MultiplicationMultiplication1)Multiply the Coefficients

2)Add the Exponents

(3.0 x 104) x (2.0 x 102) =

(3.0 x 2.0) x 104+2 = 6.0 x 106

DivisionDivision

1)Divide the coefficients

2)2)Subtract theSubtract the exponentsexponents.

3.0 x 104 = 3.0 x 104-2 = 1.5 x 102

2.0 x 102 2.0

Fixing the exponent:Fixing the exponent:

Move the decimal 1 space to the Move the decimal 1 space to the Left Left for every time you for every time you ADD ADD ONEONE to the exponent to the exponent

Move the decimal 1 to the Move the decimal 1 to the RightRight for every time you for every time you SUBTRACT SUBTRACT ONEONE from the exponent from the exponent

Addition and Addition and SubtractionSubtraction

1)Make the exponents the same. (pick highest exponent)

2) Add or Subtract the coefficients(5.40 x 103) + (6.0 x 102) =

(5.40 x 103) + (0.60 x 100.60 x 1033) = 6.00 x 103

Units of MeasurementUnits of Measurement

Measurements include two parts: Measurements include two parts: a a NumberNumber and and ScaleScale (units) … a (units) … a number without units is number without units is worthless!worthless!

The Fundamental SI UnitsThe Fundamental SI UnitsPhysical QuantityPhysical Quantity UnitUnit

AbbreviationAbbreviation

MassMass KilogramKilogram kgkg

LengthLength MeterMeter mm

TimeTime SecondSecond s (sec)s (sec)

TemperatureTemperature KelvinKelvin KK

Amount of substanceAmount of substance MoleMolemolmol

Electric currentElectric current AmpereAmpere AA

Luminous intensityLuminous intensity CandelaCandela cdcd

Standard SI prefixes for ChemistryStandard SI prefixes for ChemistryPrefixPrefix Unit Unit

AbbreviatioAbbreviationn

ExponentExponent(numerical value (numerical value

compared to base)compared to base)

MegaMega MM 1010-6-6

KiloKilo KK 1010-3-3

DeciDeci dd 101011

CentiCenti cc 101022

MilliMilli mm 101033

MicroMicro 101066

NanoNano nn 101099

PicoPico pp 10101212

TemperatureTemperature Celsius (Celsius (ooC) and Kelvin (K):C) and Kelvin (K):

1.1. K = K = ooC + 273C + 273

2.2. ooC = K – 273C = K – 273

3.3. The size of the temperature unit is The size of the temperature unit is the samethe same

FahrenheitFahrenheit

1.1. ooC = (5/9)(C = (5/9)(ooF – 32)F – 32)

2.2. ooF = (9/5)(F = (9/5)(ooC) + 32C) + 32

DensityDensity

The amount of mass in a unit of The amount of mass in a unit of volume of a substancevolume of a substance

Density = Mass / VolumeDensity = Mass / Volume

Uncertainty in MeasurementUncertainty in Measurement

A digit that must be A digit that must be estimatedestimated isis called called uncertainuncertain. A . A measurementmeasurement always has some always has some degree of uncertainty because…degree of uncertainty because…

1.1. it is performed with instrumentsit is performed with instruments2.2. no instrument can read an no instrument can read an

infinite number of decimal placesinfinite number of decimal places

is a measure of how close a measurement comes to the actual or true value.

is a measure of how close a series of measurements are to one another.

If all three darts were on the bullseye, you would be both accurateaccurate and preciseprecise.

ErrorsErrorsRandom Error (Indeterminate Error)Random Error (Indeterminate Error)

1.1. Measurement may be high or lowMeasurement may be high or low

2.2. Caused by interpretation of uncertain Caused by interpretation of uncertain digit or procedural ineptnessdigit or procedural ineptness

Systematic Error (Determinate Error)Systematic Error (Determinate Error)

1.1. Always occurs in the same directionAlways occurs in the same direction

2.2. Caused by poor technique or incorrect Caused by poor technique or incorrect calibration (gun sight set high/low; calibration (gun sight set high/low; balance improperly zeroed, balance improperly zeroed, thermometer improperly markedthermometer improperly marked

accepted value - experimental value

accepted valueaccepted value = the correct value

experimental valueexperimental value = the value measured in the lab

is the absolute value of the errorerror divided by the accepted valueaccepted value, multiplied by 100%.

% Error = error x 100%

accepted value

All of the digits that are known, plus a last digit that is estimated.

Sig. Figs. Matter all year, on all assignments, make sure to follow rules!

For AP test… good rule of thumb to use3 significant figures (graders give you a+/- 1 cushion)

1) Nonzero digits are always 1) Nonzero digits are always significant.significant.

ex: 1, 2, 3, 4…9ex: 1, 2, 3, 4…9

Rules to Determine if a digit is Rules to Determine if a digit is Significant:Significant:

Rules to Determine if a digit is Rules to Determine if a digit is Significant:Significant:

2) Zeros between nonzero 2) Zeros between nonzero digits are significantdigits are significant

Ex: 2005 , 107 , 250000023Ex: 2005 , 107 , 250000023

4 3 9

Rules to Determine if a digit is Rules to Determine if a digit is Significant:Significant:

3) Leftmost zeros appearing in 3) Leftmost zeros appearing in front of nonzero digits are front of nonzero digits are NOT SIGNIFICANTNOT SIGNIFICANT. They act . They act as placeholders.as placeholders.

Ex: 0.Ex: 0.00007, 7, 00.12 , 0..12 , 0.000000434434

1 2 3

Rules to Determine if a digit is Rules to Determine if a digit is Significant:Significant:

4) Zeros at the end of a 4) Zeros at the end of a number and to the right of a number and to the right of a decimal point are always decimal point are always significant.significant.

Ex: 34.00, 10.00, 0.400Ex: 34.00, 10.00, 0.4004 4 3

Rules to Determine if a digit is Rules to Determine if a digit is Significant:Significant:

5) Zeros at the end of a whole 5) Zeros at the end of a whole number are not significant.number are not significant.

Ex: 10, 100, 4500 … Ex: 10, 100, 4500 …

1 1 2

Pacific/Atlantic RulePacific/Atlantic Rule If a decimal is If a decimal is PresentPresent, start on , start on

the the PacificPacific side of the number side of the number and every number counts after and every number counts after the first non-zero digitthe first non-zero digit

If a decimal is If a decimal is AbsentAbsent, start on , start on the the AtlanticAtlantic side of the number side of the number and every number counts after and every number counts after the first non-zero digit.the first non-zero digit.

A) 5000 =

B) 0.0234 =

C) 10.0052 =

D) 25.000 =

1 sig. fig.

3 sig. figs.

6 sig. figs.

5 sig. figs.

Round the answer to the same number of significant figures as the measurement with the least number of significant figures.

7.55 x 0.34 = 2.567 = 2.6

CaluculationCaluculation Calculator SaysCalculator SaysAnswerAnswer3.24m x 7.0 m 22.68m2 10.2 m2

100.0g / 23.7g 4.21940 g/cm34.22 g/cm3

0.02cm x 2.371cm

710m / 3.0s

0.04742cm2

236.66667 m/s

0.05cm2

240 m/s

Round the answer to the same number of decimal places as the measurement with the least number of decimal places.

1.2 + 3.52 + 2.431 = 7.151 = 7.2

CaluculationCaluculation Calculator SaysCalculator SaysAnswerAnswer3.24m + 7.0 m 10.24 m 10.2 m

100.0g – 23.73g 76.27g 76.3g

0.02cm + 2.371cm

713.1L – 3.872L

2.391cm

709.228L

2.39cm

709.2L

Dimensional AnalysisDimensional Analysis

Unit Conversion Questions:Unit Conversion Questions: What unit am I given?What unit am I given? What units must be in my What units must be in my

answer?answer? What is (are) my conversion What is (are) my conversion

factor(s)?factor(s)?

Full credit will not be given on D.A. Full credit will not be given on D.A. problems in which you do not problems in which you do not

perform the following:perform the following:

1.1. Observe sig. fig. rulesObserve sig. fig. rules

2.2. Label all steps with correct unitsLabel all steps with correct units

3.3. Correctly label and ID answerCorrectly label and ID answer

4.4. Solve problem in manner that can Solve problem in manner that can be understood by the readerbe understood by the reader

Why important? Why am I being Why important? Why am I being a jerk about this?a jerk about this?