Scientific methodMethod for answering questions• Make an observation • Ask a question (hypothesis)• Obtain facts (experiment)• Explain experiment (conclusion)• Theory or law

Measurements – SI unitsQuantity Name UnitLength Meter MMass Kilogram

(gram)Kg(g)

Time Second S (sec)Temperature Kelvin KAmount Mole Mole

Metric prefixesPrefix Abbrev factorKilo K 103

Deci d 10-1 (1/10)Centi c 10-2 (1/100)Milli m 10-3 (1/1000)Micro 10-6 (1/1,000,000)Nano n 10-9

(1/1,000,000,000)

Derived units Area

L x w Volume

L x w h

For more see appendix p 806Agenda p R-11

Reliability

Precisionability to repeat measurement

Accuracyability to get accepted value

Bulls eye

Uncertainty in Measurement

Measurements involve estimation in last digit

Remember …..

Significant digits The certain and 1 estimated digit of

a measurement

Atlantic-Pacific ruleif a decimal is Absent, count

first non-zero number from Atlantic side

if a decimal is Present, count first non-zero number from the Pacific side

Practice

How many significant figures in each?

1. .00987 2. 987003. 987.004. 987009875. 987.00987

33588

Calculations

Addition/subtractioncount least places after the

decimal

Multiplication/divisioncount the least number of significant digit

Practice Calculations

1. 2.3 x 11.0090=2. 15.00 =

3.73. 11 + 2.34 + 900.0560=4. (3.2 x 103)(6.003 x 10-2)=5. 8.90 x 106 = 5.1 x 10 -9

Problem Solving 1. Write known and unknown 2. Write equation 3. Use factor label method (start with

the units of the known) 4. Calculate 5. Circle answer with correct

significant figures

Ratios• Speed Distance time

• Density mass volume

Ratios of equal terms• 1 m = 10 dm

1m 10 dm 10 dm 1m

• 1 min = 60 sec1 min 60 sec60 sec 1 min

For more see agenda p R-10

Factor label=Dimensional AnalysisUsing units to solve problems

Show work using units

1.   How many seconds in 14 days? Show work.

2. How many mL in 1.09 kL?3. Convert 3.4 g/ml to dg/cL

Graphs Create a good data table

Computer Graphing

Excel A- x axis,flask size (ml) B- Y axis, time (sec) Highlight all 2columns Chart Wizard X,Y scatter middle chart, left column Title (include your name), label both axis New sheet Unshade background Print 1 to science dept

Excel

A- x axis (volume), B- Y axis (mass) Highlight all 2columns, Chart Wizard X,Y scatter top chart, left column Title (include your name), label both axis New sheet Chart

add trend line Linear

options tab Check off intercept=0 display equation chart,

Unshade background/format plot area/white box Print to lexchex or sci dept

Slope

Rise = y2-y1 = m2-m1 = mass Run x2-x1 v2-v1 volume

Pick 2 points on the line. Write the coordinates (x1,y1)(x2,y2)Calculate the density

Do this on your graph.

Pure Matter

Elementscannot be broken down by chemical processes

CompoundChemical combination of elements(share or transfer of electrons)

States of Matter Gas Liquid Solid Plasma

What’s the Difference?

Solids are ordered Liquids haveSome order

Gases are almostrandom

MatterAnything that has mass and volume

do not copy in notebook Density Pressure

ContainerSolid High not affected own

shape

Liquid High not affected takes shape

Gas low affected fills

Plasma low affected fills

Changes in Matter

Physical changes Involve no change in composition Physical properties:Boiling/melting point, density, color, odor, ductile

Chemical changes Involves a change in composition

Heat changeColor changeGas evolvedPrecipitate formed

Chemical properties: combustion, reactivity

Changes of State What is happening to the molecules as ice

heats up? Change from one state to another takes energy

Is the melting point and freezing point the same? Heat of fusion Is the evaporation and condensation pt the same? Heat of evaporation What is the difference between steamed and

boiled?

Cooling Curve

50

100

150

200

250

Tem

p (D

egre

es C

)

0 50 100 150 200 250 Time (seconds)

Temperature versus Time

Liquid

Solid

GasCondense/evaporate

Freeze/melt

Temperature Scales Fahrenheit was a thermometer maker

• He was a very good thermometer maker• Why do we still use his scale?

Celsius is based on the melting point and boiling point of water• 0o C = Freezing point of Swiss Alps snow• 100o C = Boiling point at sea level

Why does it have to be at sea level?• Why is this better than Fahrenheit?