# Unit 1-3 SI units Do now: read chapter 1.6.

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Unit 1-3 SI units Do now: read chapter 1.6

How much does it cost? UNITS MATTER!!

The Nature of Measurement
A Measurement is a quantitative observation consisting of TWO parts Part 1 - number Part 2 - scale (unit) Examples: 20 grams 6.63 x seconds

The Fundamental SI Units (le Système International, SI)

The three major temperature scales.
TK = TC TC = TK –

Temperature scales Celsius scale Kelvin scale
based on freezing and boiling points of water (0 oC – 100 oC) Kelvin scale based on absolute zero (0 K) temperature at which particles are at lowest possible energy NO negative numbers

K = oC + 273 oC = K – 273

Converting Between Celsius & Fahrenheit
TC = (TF – 32)X 5/9 TF = TC x 9/ You don’t need to memorize the conversion between TC and TF

SI Prefixes Common to Chemistry
Unit Abbr. Exponent Kilo k 103 Deci d 10-1 Centi c 10-2 Milli m 10-3 Micro 10-6

SI Prefixes The Great Man King Henry Died By Drinking Chocolate Milk
Monday Night Partying Tera- Giga- Mega- Kilo- Hecto- Deka- Base Deci- Centi- Milli- Micro- Nano- Pico- 1 T(base) = (base) = 1012 (base) 1 G(base) = (base) = 109 (base) 1 M(base) = (base) = 106 (base) 1 k(base) = (base) = 103 (base) 1 h(base) = 100 (base) = 102 (base) 1 da(base) = 101 (base) 1 (base) = 1 (base) 1 d(base) = 10-1 (base) 1 c(base) = 10-2 (base) 1 m (base) = 10-3(base) 1 µ(base) = (base) = 10-6(base) 1 n(base) = (base) = 10-9(base) 1 p(base) = (base) = 10-12(base)

SI Prefix Conversions tera- T 1012 Decimal move left
Symbol Factor tera- T 1012 giga- G 109 mega- M 106 kilo- k 103 hecto- h 102 deka- da 101 Decimal move left Decimal move right BASE UNIT --- 100 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12

Prefix conversion g m L 103 102 101 10-1 10-2 10-3 kilo hecto deka
Base unit deci centi milli Conversions between prefixes 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.

Example #1: Convert 18 liters to milliliters
Metric Conversions g m L 103 102 101 10-1 10-2 10-3 kilo hecto deka Base unit deci centi milli 1 2 3 18 L 18 liters = milliliters Example #1: Convert 18 liters to milliliters

Example #2: Convert 450 milligrams to grams
Metric Conversions g m L 103 102 101 10-1 10-2 10-3 kilo hecto deka Base unit deci centi milli 3 2 1 450 mg = g 450 mg Example #2: Convert 450 milligrams to grams

Example #3: Convert 20 kilograms to milligrams
Metric Conversions g m L 103 102 101 10-1 10-2 10-3 kilo hecto deka Base unit deci centi milli 1 2 3 4 5 6 20 kg 20 kg = mg Example #3: Convert 20 kilograms to milligrams

Derived SI units Volume= (length)3 SI unit of V: m3
Commonly used units of V: Liter(L)= dm3 Milliliter(ml)=cm3 Volume= (length)3

SI Prefix Conversions-concept check
a. cm to m b. m3 to L c. ns to s d. kg to g

SI Prefix Conversions-concept check
20 cm = ______________ m 2) L = ______________ mL 3) 45 m = ______________ m

Homework Handout Due next class.