Units of MeasurementUnits of Measurement

AgendaAgenda Review elementsReview elements Lab Reports TuesdayLab Reports Tuesday SongSong Notes on Units of Measurement & SNNotes on Units of Measurement & SN HomeworkHomework

FFfluorinefluorine

OOoxygenoxygen

seleniumseleniumSeSe

NNnitrogennitrogen

chlorinechlorineClCl

SSsulfursulfur

PPphosphorusphosphorus

BrBrbrominebromine

strontiumstrontiumSrSr

IIIodineIodine

arsenicarsenicAsAs

GaGagalliumgallium

aluminumaluminumAlAl

Percent error formula?Percent error formula?

Units of MeasurementUnits of MeasurementDate:Date:

SongSong

SI UNITSSI UNITS

International System of UnitsInternational System of Units Measurements used around the world so Measurements used around the world so

results are comparable.results are comparable.

Base UnitsBase Units

How would you define base units?How would you define base units?

Basic unit of measurementBasic unit of measurement

LengthLength

Meter, mMeter, m

MassMass

Kilogram, kgKilogram, kg

Amount of SubstanceAmount of Substance

Mole, molMole, mol

TemperatureTemperature Kelvin, KKelvin, K

NO degree sign!NO degree sign!

Absolute Temperature Absolute Temperature no negative # no negative # At absolute 0, all molecular motion stopsAt absolute 0, all molecular motion stops

Celsius to KelvinCelsius to Kelvin ooC + 273 = KC + 273 = K

Celsius to FahrenheitCelsius to Fahrenheit ooF = (9/5*F = (9/5*ooC) + 32C) + 32

Derived UnitsDerived Units

DefineDefine

A combination of base unitsA combination of base units

VolumeVolume

mm33

Length x width x heightLength x width x height

Not very practical unit so we’ll use LNot very practical unit so we’ll use L

1 cm1 cm33 = 1 mL = 1 mL 1000 L = 1 m1000 L = 1 m33

DensityDensity

Mass / volumeMass / volume Kg/mKg/m33

More practical g/mLMore practical g/mL

PressurePressure

Force / AreaForce / Area

mmHg, torr, kPa, atmmmHg, torr, kPa, atm

Reliability of MeasurementsReliability of Measurements

Accuracy: the closeness of a Accuracy: the closeness of a singlesingle measurement to its true value.measurement to its true value. Hitting the bullseye.Hitting the bullseye.

Precision: the closeness of a Precision: the closeness of a setset of values of values to each other.to each other.

Measurement ExplorationMeasurement Exploration

Which measuring devices are more Which measuring devices are more precise?precise?

Basic FormulaBasic Formula

A * 10A * 10exponentexponent

A number between 1 and 10A number between 1 and 10

If original number > than 1, exponent +If original number > than 1, exponent + If original # < than 1, exponent -If original # < than 1, exponent -

PracticePractice

30003000 26530002653000 5460054600 130130 0.0000560.000056 0.004560.00456 0.078690.07869 3.14159263.1415926

HomeworkHomework