Aim: How to use Dimensional Analysis to Convert from One unit to Another DO Now: Answer the following questions in your notebook in the following format “60 seconds = 1 minute” How many seconds are in minute? How many minutes are in an hour? How many hours are in a day? How many days are in a week? How many weeks are in a year?

Common units used in Chemistry

What is a Unit Conversion? A unit conversion is a changing of one unit to another using a conversion factor.

What is a conversion factor A conversion factor is an equality used to change one set of units to another Examples of conversion factors 60 sec = 1 min 1000 m = 1 km 2.2 lbs = 1 kg

Unit Conversion 1 Foot = 12 inches 1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 1 A conversion factor can be written as two different fractions 1 Foot = 12 inches 1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 1 12 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 = 1

Using dimensional analysis Given value x conversion factor Given value x 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑢𝑛𝑖𝑡 𝑔𝑖𝑣𝑒𝑛 𝑢𝑛𝑖𝑡

Unit Conversion “ conversion factors” How many inches are in 3 ft.? 1 𝑓𝑜𝑜𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 = 1 12 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 = 1 “ conversion factors” How many inches are in 3 ft.? ( 3 feet ) ( 12 𝑖𝑛𝑐ℎ𝑒𝑠 1 𝑓𝑜𝑜𝑡 ) = 36 inches Conversion Factor

( ) ______ How many cm are in 1.32 meters? equality: 1 m = 100 cm applicable conversion factors: ______ 1 m 100 cm ______ 1 m 100 cm or ( ) ______ 1 m 100 cm 132 cm X cm = 1.32 m = We use the idea of unit cancellation to decide upon which one of the two conversion factors we choose.

Again, the units must cancel. How many meters is 8.72 cm? equality: 1 m = 100 cm applicable conversion factors: ______ 1 m 100 cm ______ 1 m 100 cm or ( ) ______ 1 m 100 cm 0.0872 m X m = 8.72 cm = Again, the units must cancel.

Again, the units must cancel. How many feet is 39.37 inches? equality: 1 ft = 12 in applicable conversion factors: ______ 1 ft 12 in ______ 1 ft 12 in or ( ) ____ 1 ft 12 in 3.28 ft X ft = 39.37 in = Again, the units must cancel.

Exit Slip On a separate sheet of paper explain how conversion factors are used to convert between units.