 Sometimes, non-SI units are used  Liter, Celsius, calorie  Some are derived units  They are made by joining other units  Speed = miles/hour (distance/time)  Density = grams/mL (mass/volume)

SI Prefixes – Page 74 Common to Chemistry Prefix Unit Abbreviation MeaningExponent Kilo-k thousand 10 3 Deci-d tenth Centi-c hundredth Milli-m thousandth Micro-  millionth Nano-n billionth 10 -9

METRIC PREFIXES Don’t copy this…use the hand out!

Volume (derived)  The space occupied by any sample of matter.  derived from units of length  SI unit = cubic meter (m 3 )  Everyday unit = Liter (L), which is non-SI.  (Note: 1mL = 1cm 3 )

Units of Temperature Temperature is a measure of how hot or cold an object is. – Heat moves from the object at the higher temperature to the object at the lower temperature. We use two units of temperature: – Celsius – Kelvin (Measured with a thermometer.)

Units of Temperature Celsius scale defined by two readily determined temperatures: – Freezing point of water = 0 o C – Boiling point of water = 100 o C Kelvin scale absolute zero = 0 K (thus no negative values) formula to convert: K = o C + 273

- Page 78

Units of Energy Energy is the capacity to do work, or to produce heat. – Two common units are: 1) Joule (J) = the SI unit of energy 2) calorie (cal) = the heat needed to raise 1 gram of water by 1 o C

Section 3.3 Conversion Problems

Conversion factors A “ratio” of equivalent measurements Start with two things that are the same: one meter is one hundred centimeters write it as an equation 1 m = 100 cm

Conversion factors 100 cm1 m= 100 cm 1 m

Practice by writing the two possible conversion factors for the following: Between kilograms and grams between decimeters and meters using qt. = 1.00 L

METRIC PREFIXES Don’t copy this…use the hand out!

What are they good for? Metric Conversions Worksheet I: prefix and a base unit – Look at the examples on the board – Work on the worksheet in class and finish it for homework – Come to class with questions tomorrow!