UNIT 1A: MEASUREMENT IN CHEMISTRY MEASUREMENT AT THE CONCLUSION OF OUR TIME TOGETHER, YOU SHOULD BE ABLE TO: 1. Explain the difference between the two.

UNIT 1A: MEASUREMENT

INCHEMISTRY

MEASUREMENTAT THE CONCLUSION OF OUR

TIME 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 each

SI MEASUREMENT

• Le Système International d ‘Unités

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

• International Standards are kept in France.

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

• Liberia and Myanmar are changing over.

Information from U.S. Metric Association

Liberia

BASE 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

TYPES OF OBSERVATIONS AND MEASUREMENTS – PAGE 25

• We make QUALITATIVE observations of reactions — changes in color and physical state.

• We also make QUANTITATIVE observations that involve MEASUREMENTS with numbers and units.

STATING A QUANTITATIVE MEASUREMENT

In every measurement there is a

Number (Quantity) followed by a

Unit from a measuring device

METRIC PREFIXES – PAGE 40

METRIC PREFIXES – PAGE 40

You Will Need to Know:

The Grand Master King Henry Died by Drinking Chocolate Milk Monday Night

Prior

METRIC PREFIXES YOU NEED TO KNOW – PAGE 40

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

110

103

10-310-210-1

10-6

10-9

ACCURACY & PRECISION – PAGE 25

MEASUREMENT? – PAGE 26

MEASUREMENT? – PAGE 26

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. WEIGHT• Mass: Amount

of Matter • (grams,

measured with a BALANCE)

• Weight: Force exerted by the

mass, only present with

gravity • (pounds,

measured with a Scale)

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

UNIT FOR VOLUME

1 Meter Cubed

Note: A Derived Unit!!

To Big, So Generally Use the 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 Liter

mLmL

1 dm1 dm33 = = 1 L

1 cm1 cm3 3 = = 1 mL

OTHER 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 ENERGY

• Joule JJoule J

• calorie 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

MEASUREMENTLET’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 CHECK

Match L) length M) mass V) volume

____ A. A bag of tomatoes is 4.6 kg.

____ B. A person is 2.0 m tall.

____ C. A medication contains 0.50 g Aspirin.

____ D. A bottle contains 1.5 L of water.

M

L

M

V

LEARNING 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?

LEARNING CHECK

1. 1000 m = 1 ___ a) mm b) km c) dm

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

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

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

LEARNING CHECK

Select the unit you would use to measure 1. Your height

a) millimeters b) meters c) kilometers

2. Your mass a) milligrams b) grams c) kilograms

3. The distance between two cities a) millimeters b) meters c) kilometers

4. The width of an arterya) millimeters b) meters c) kilometers