MeasurementMeasurementInIn

ChemistryChemistry

MeasurementMeasurementAt the conclusion of our time At the conclusion of our time

together, you should be able to:together, you should be able to:

1. Explain the difference between the two types of observations

2. Give examples of 5 basic SI measuring units3. Give examples of 3 different derived units

from the basic SI units4. Vary the amounts of the SI measuring units

with 10 different prefixes and define each5. Explain the difference between mass and

weight6. List and explain 5 different units for volume.

Types of Observations and Types of Observations and MeasurementsMeasurements

We makeWe make QUALITATIVEQUALITATIVE observations of observations of reactions — changes in color and reactions — changes in color and physical state.physical state.

We also makeWe also make QUANTITATIVEQUANTITATIVE observations that involve observations that involve MEASUREMENTSMEASUREMENTS with numbers and with numbers and units. units.

Some Tools for MeasurementSome Tools for Measurement

Which tool(s) Which tool(s) would you use to would you use to measure:measure:

A.A. temperature temperature

B.B. volume volume

C.C. time time

D.D. weight weight

Stating a Quantitative Stating a Quantitative MeasurementMeasurement

In every measurement there is aIn every measurement there is a

Number (Quantity) Number (Quantity) followed by a followed by a

Unit Unit from a measuring devicefrom a measuring device

Quantitative Measurements in Chemistry Must Include Units!

Standards of Quantitative Standards of Quantitative MeasurementMeasurement

When we measure, we use a measuring When we measure, we use a measuring tool to compare some dimension of an tool to compare some dimension of an object to a standard.object to a standard.

For example, at one time the For example, at one time the standard for length was the standard for length was the king’s king’s footfoot. What are some . What are some

problems with this standard?problems with this standard?

SI MeasurementSI Measurement

Le Système International Le Système International d‘Unités d‘Unités

Adopted in 1960 by the Adopted in 1960 by the General Conference on General Conference on Weights and Measures.Weights and Measures.

International Standards International Standards are kept in France.are kept in France.

Among countries with Among countries with non-metric usage, the non-metric usage, the U.SU.S.. is the is the only country only country significantly holding outsignificantly holding out. . The The U.SU.S. officially adopted . officially adopted SI in 1866.SI in 1866.

LiberiaLiberia and and MyanmarMyanmar are are changing over.changing over.

Information from U.S. Metric Association

Liberia

Base SI UnitsBase SI Units

QuantityQuantity UnitUnit SymbolSymbol

LengthLength metermeter mm

MassMass kilogramkilogram kgkg

TemperatureTemperature kelvinkelvin KK

TimeTime secondsecond ss

Amount of Amount of SubstanceSubstance

molemole molmol

Luminous Luminous IntensityIntensity

candelacandela cdcd

Electric CurrentElectric Current ampereampere aa

Units Of Measurement You Must Units Of Measurement You Must KnowKnow

Use Use SI units SI units — based on the metric system— based on the metric system

Length Length

MassMass

VolumeVolume

TimeTime

TemperatureTemperature

meter, m

kilogram, kg

seconds, s

kelvin, K

liter, L

Unit for LengthUnit for Length

1 Meter1 Meter

Note: Not Note: Not FootFoot!!!!

Metric PrefixesMetric Prefixes

Kilo-Kilo- means 1000 of that unit means 1000 of that unit

1 kilometer (km) = 1000 meters (m)1 kilometer (km) = 1000 meters (m)

Centi-Centi- means 1/100 of that unit means 1/100 of that unit

1 meter (m) = 1 meter (m) = 100 centimeters (cm) 100 centimeters (cm)

1 dollar = 1 dollar = 100 cents 100 cents

Milli-Milli- means 1/1000 of that unit means 1/1000 of that unit

1 meter (m) = 1 meter (m) = 1000 millimeters 1000 millimeters

(mm)(mm)

1 millenium =1 millenium = 1000 years 1000 years

Metric PrefixesMetric Prefixes

Metric PrefixesMetric Prefixes

You Will Need to Know:

Grand Master King Henry Died by DrinKing Chocolate Milk Monday Night

Metric Prefixes You Need to KnowMetric Prefixes You Need to Know

110

103

10-310-210-1

10-6

10-9

1 meter (m)

1 kilometer (km)

1 dm (decimeter)1 cm (centimeter)1 mm (millimeter)

1 m (micrometer)

1 nm (nanometer)

103 meters = 1 km

10 dm = 1 m100 cm = 1 m103 mm = 1 m

106 m = 1 m

109 nm = 1 m

Unit for MassUnit for Mass

1 Kilogram1 Kilogram

Note: Not Note: Not GramGram!!!!

Unit for WeightUnit for Weight

1 Newton1 Newton

1 N = kg m/s1 N = kg m/s22

A Weighty ProblemA Weighty Problem

On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat.

1 lb = 1 N

1 lb = 4.45 N

“This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses ‘till the end of time.”

Weight is force of the gravitational pull on an object. It would be different on the moon than it is on earth.

Mass is a measure of the amount of matter in an object.Mass is a measure of the amount of matter in an object.

Mass and weight are directly related as long as we remain on earth at the same elevation. That is, if one object has twice the mass of another, then its weight on earth would also be

twice as large.

However, if we take the same object to Denver, Colorado, the mass stays the same but the weight would be

different. Why??

Mass and Weight

Mass vs. WeightMass vs. Weight MassMass: Amount : Amount

of Matter of Matter (grams, (grams,

measured with measured with a BALANCE)a BALANCE)

WeightWeight: Force : Force exerted by the exerted by the

mass, only mass, only present with present with

gravity gravity (pounds, (pounds,

measured with measured with a a SCALESCALE))

Can you hear Can you hear me now?me now?

Unit for VolumeUnit for Volume

1 Meter Cubed1 Meter Cubed

Note: A Note: A DerivedDerived Unit!! Unit!!

Too Big, So Generally Use the Too Big, So Generally Use the LiterLiter

What is a Liter??What is a Liter??

Length and Volume

1 m = 10 dm therefore 1 m3 = 103 dm3

1 dm = 10 cm therefore 1 dm3 = 103 cm3

1 L = 1 dm3 and 1 L = 103 mL

so

1 L = 1 dm3 = 103 mL = 103 cm3 = 103 cc

so

This means that 1 milliliter (mL) is the same as 1 cubic centimeter (cc). These terms are often

used interchangeably.

Units for Volume Units for Volume

mm33

cmcm3 3

dmdm33

L L LiterLiter

mLmL

1 dm1 dm33 = = 1 L1 L

1 cm1 cm3 3 = = 1 mL1 mL

Other Derived SI UnitsOther Derived SI Units

QuantityQuantity UnitUnit SymbolSymbol

VolumeVolume cubic metercubic meter mm33

DensityDensity kilograms per kilograms per cubic metercubic meter

kg/mkg/m33

SpeedSpeed meter per secondmeter per second m/sm/s

NewtonNewton kg m/ skg m/ s22 NN

EnergyEnergy Joule (kg mJoule (kg m22/s/s22)) JJ

PressurePressure Pascal (kg/msPascal (kg/ms22)) PaPa

Units for EnergyUnits for Energy

Joule JJoule J

caloriecalorie 1 cal = 4.184 J 1 cal = 4.184 J

1 cal = quantity of heat needed to raise the 1 cal = quantity of heat needed to raise the temperature of 1 g of water by 1 temperature of 1 g of water by 1 ooC.C.

1 kcal = 1 kcal = 10001000 cal cal

MeasurementMeasurementLet’s see if you can:Let’s see if you can:

1. Explain the difference between the two types of observations

2. Give examples of 5 basic SI measuring units3. Give examples of 3 different derived units

from the basic SI units4. Vary the amounts of the SI measuring units

with 10 different prefixes and define each5. Explain the difference between mass and

weight6. List and explain 5 different units for volume.

Learning CheckLearning Check

Match Match L) lengthL) length M) mass M) mass V) volume V) volume

____ A. A bag of tomatoes is 4.6 kg.____ A. A bag of tomatoes is 4.6 kg.

____ B. A person is 2.0 m tall.____ B. A person is 2.0 m tall.

____ C. A medication contains 0.50 g Aspirin.____ C. A medication contains 0.50 g Aspirin.

____ D. A bottle contains 1.5 L of water.____ D. A bottle contains 1.5 L of water.

M

L

M

V

Learning CheckLearning Check

What are some U.S. units that are used to measure each of the following?

A. length

B. volume

C. weight

D. temperature

Which Metric Prefix is Generally Used?Which Metric Prefix is Generally Used?

Learning CheckLearning Check

1. 1000 m = 1 1. 1000 m = 1 ______ a) mm b) km c) a) mm b) km c)

dmdm

2. 0.001 g = 1 2. 0.001 g = 1 ___ ___ a) mg b) kg c) dga) mg b) kg c) dg

3. 0.1 L = 1 3. 0.1 L = 1 ______ a) mL b) cL c) dLa) mL b) cL c) dL

4. 0.01 m = 1 ___ 4. 0.01 m = 1 ___ a) mm b) cm c) dma) mm b) cm c) dm

Learning CheckLearning Check

Select the unit you would use to measure Select the unit you would use to measure

1. Your height1. Your height

a) millimeters a) millimeters b) metersb) meters c) c) kilometerskilometers

2. Your mass2. Your mass

a) milligramsa) milligrams b) gramsb) grams c) kilograms c) kilograms

3. The distance between two cities3. The distance between two cities

a) millimetersa) millimeters b) metersb) meters c) kilometers c) kilometers

4. The width of an artery4. The width of an artery

a) millimetersa) millimeters b) metersb) meters c) kilometers c) kilometers