Measurements All include a number and a unit Standardized (same worldwide) Metric system -Created in Based on 10’s & multiples of 10 -Revised in now called SI System

Units Seven base units Remainder are derived Area = l x w=m 2 Volume = l x w x h =m 3 Density = mass / volume = g / cm 3 Base units are modified in magnitude by use of prefixes

Length Base unit is Meter (m) For different measurements prefixes modify Long distanceskm Diameter of golf ballcm Thickness of CDmm

Volume Derived from units of length Base unit- m 3 Commonly used unit - liter (I) 1I = 1dm 3 = 1000 cm 3 1l = 1000 ml 1000 cm 3 = 1000 ml So: 1cm 3 = 1mI

Devices for Volume Graduated cylinder Buret Volumetric flask Volume changes with temperature, so devices are calibrated at a specific temperature, typically, 20° C or ambient room temperature.

Mass Weight- Pull of gravity Mass- Amount of matter Base unit- kg- mass of 1l Gram more commonly used unit Measuring device- balance

Temperature

Measures average kinetic energy (KE) of particles —The greater the KE, the greater the temperature Determines the direction of heat transfer —Put hand near bunsen burner flame, transfer heat to hand

Put hand near window on cold day, transfer heat to window Heat moves from higher temperature to lower temperature.

Thermometer Works because liquid (alcohol / mercury) expands more when heated than glass so column rises.

Temperature Scale Celsius —Most common in Chemistry —Named for Anders Celsius (Swedish astronomer) 0°C- water freezes 100°C- water boils

Kelvin Scale Base unit in SI System Named for Lord Kelvin (Scottish physicist & mathematician) 0 K = absolute zero K— water freezes K—water boils 1° C = 1 K

Conversions K = °C °C = K Room temperature is about 20°C. What is the temperature in Kelvin? K = 20°C K = 293K

Practice What is the temperature of absolute zero in Celsius? °C = K = = -273°C

Practice The temperature on a winter day is -12°C. What is this temperature in Kelvin? K = °C = = 261K