The SI System of Measurement

The Nature of Measurement

Part 1 - numberPart 2 - scale (unit)

Examples:20 grams

6.63 x 10-34 Joule·seconds

A Measurement is a quantitative observation consisting of TWO parts

The Fundamental SI Units (le Système International, SI)

Physical Quantity Name Abbreviation

Mass kilogram kg

Length meter m

Time second s

Temperature Kelvin K

Electric Current Ampere A

Amount of Substance mole mol

Luminous I ntensity candela cd

SI PrefixesCommon to Chemistry

Prefix Unit Abbr. ExponentKilo k 103

Deci d 10-1

Centi c 10-2

Milli m 10-3

Micro 10-6

Metric ConversionsgmL 10-1 10-2 10-3101102103

Baseunit

deci centi millidekahectokilo

Conversions in the metric system are merely a matter of moving a decimal point. The “base unit” means the you have a quantity (grams, meters, Liters, etc without a prefix.

Metric ConversionsgmL 10-1 10-2 10-3101102103

Baseunit

deci centi millidekahectokilo

Example #1: Convert 18 liters to milliliters

18 L1 2 3

18 liters = 18 000 milliliters

Metric ConversionsgmL 10-1 10-2 10-3101102103

Baseunit

deci centi millidekahectokilo

Example #2: Convert 450 milligrams to grams

123450 mg450 mg = 0.450 g

Metric ConversionsgmL 10-1 10-2 10-3101102103

Baseunit

deci centi millidekahectokilo

Example #3: Convert 20 kilograms to milligrams

20 kg1 2 3 4 5 6

20 kg = 20 000 000 mg

Metric Conversion Practice-

Dimensional Analysis

Decimal Ladder

DA formatGiven unit always goes first

Given unit

=Given unit

new unit new unit

Problem #1Convert 400 mL to Liters

400 mL= L

mL

L

1 000

1 .400

= 0.4 L

= 4x10-1 L

Problem #2Convert 10 meters to mm

10 m= m

mm

mm

1

1 000 10 000

= 1x104 mm

Problem #3Convert 73 grams to kg

73 g= kg

g

kg

1 000

1 0.073

= 7.3x10-2 kg

MConvert 0.02 kilometers to m

0.02 km= m

km

m

1

1 000 20

= 2x101 m

4Convert 20 centimeters to m

20 cm= m

cm

m

100

1 0.20

= 2x10-1 m

2Convert 450 milliliters to dL

450 mL= dL

mL

dL

100

1 4.5

1Convert 10 kilograms to grams

10 kg= g

kg

g

1

1 000 10 000

= 1x104 g

Temperature Change

KoC (-273)oCK (+273)

Problem #5

Convert 45oC to K

45 oC +273 =318K

Problem #6

Convert K to oC

746K-273 =473K

Molar Conversions

Mole-the amount of a substance• 1 mol of any substance equals

6.022x1023 particles– atoms– molecules

Take a look at the Periodic Table of Elements• 1 mol of Na is 22.99 g• 1 mol of H20 is 18.02g

Molar Mass

The amount of matter in 1 mole• 10.81 g B in 1 mol B• 58.69 g Ni in 1 mol Ni• ______ g Fe in 1 mol Fe• 12.01 g C in ___ mol C

55.851

Problem #7Convert 54g Na to mol Na

54 g Na= mol

Nag Na

mol Na23

12.4

Problem #86.3 mol Al to g Al

6.3 mol Al= g Al

mol Al

g Al

1

26.98 170

Problem #10Convert 175 mL to cm3

175 mL= cm3

mL

cm3

1

1175

= 1.75x102 cm3