chemistry conversions dimensional analysis and atoms, elements, compounds
TRANSCRIPT
SI PrefixesPrefix Abbreviation Exponential
MultiplierMeaning Example using length
Kilo- k 103 1000 1 kilometer (km) = 1000 m
Hecto- h 102 100 1 hectometer (hm) = 100 m
Deka- da 101 10 1 dekameter (dam) = 10 m
100 1 1 meter (m)
Deci- d 10-1 1/10 1 decimeter (dm) = 0.1 m
Centi- c 10-2 1/100 1 centimeter (cm) = 0.01 m
Milli- m 10-3 1/1000 1 millimeter (mm) = 0.001 m
Converting From One Unit to Another
• We will convert A LOT!
• Uses a technique called Factor Label Method
• Cancels out units and does the math for you!!
Factor-Label Method for Conversions
• Mathematics used Numbers, rather than Quantities
• Chemistry uses these same Numbers along with the value’s Units
• A Number is useless without its unit
• Units give the Number an actual meaning
Conversion Factors
• A conversion Factor is needed to go from one unit to another
• You must first know how much of one thing is of another before making any conversions
• We all know 1 foot is made up of 12 inchesSO…
• The conversion factor needed to go from feet to inches or from inches to feet is
1 foot / 12 inches or 12 inches / 1 foot,Respectively.
Conversion Factors
Let’s try using 1 pound = 0.454 Kilograms
1 inch = 2.54 centimeters1 gallon = 3.71 Liters
1 mile = 1.61 Kilometers
Conversions
1 pound = 0.454 Kg
157 lb
1 lb
0.454 kg
The “Heart” of the problem is where the conversion actually takes place. This is where your conversion factor does its work.
Conversions
1 pound = 0.454 Kg
157 lb
1 lb
0.454 kg
( 157 * 0.454 ) / 1 = 71
= 71 kgSo yes, with the proper units 157 lb does equal 71 kg, but without units the values are not the same, as we do not know the correct representation numbers.
Units
• Units are everything. They give any value an actual meaning and interpretation.
• Always carry your units through, rewriting them until you reach a final value, or you will be lost.
English System (American System)
• 1 foot = 12 inches• 1 yard = 3 feet• 1 mile = 5,280 feet = 1,760 yards• 1 gallon = 16 cups = 4 quarts = 8 pints• 1 pound = 16 ounces
Conversions Factors:
Converting with English Units
Convert 15.41 yards to inches:
Conversion Factors:• 1 yard = 3 feet• 1 foot = 12 inches
Question:
Converting with Metric Units
Convert 15.41 yards to inches:
15.41 yd
Conversion Factors:• 1 yard = 3 feet• 1 foot = 12 inches
Converting with Metric Units
Convert 15.41 yards to inches:
15.41 yd1 yd3 ft
Conversion Factors:• 1 yard = 3 feet• 1 foot = 12 inches
Converting with Metric Units
Convert 15.41 yards to inches:
15.41 yd1 yd3 ft 12 in.
1 ft
Conversion Factors:• 1 yard = 3 feet• 1 foot = 12 inches
Converting with Metric Units
Convert 15.41 yards to inches:
15.41 yd1 yd3 ft 12 in.
1 ft
= (15.4 * 3 * 12) / 1
15.41 yards = 554.76 inches
Metric System
Common Metric Prefixes:Prefix Abbreviation Value (Base Unit)
Kilometer km 1000
Hectometer hm 100
Dekameter dam 10
Base Unit (meter) meter 1
Centimeter cm 0.01
Millimeter mm 0.001
Micrometer µm 0.000001
Converting with Metric Units
Convert 0.248 km to centimeters:Conversion Factors:• 1 Kilometer = 1000 meters• 1 meter = 100 centimeters
Question:
Prefix Abbreviation Value (Base Unit)Kilometer km 1000Hectometer hm 100Dekameter dam 10Base Unit (meter) meter 1Centimeter cm 0.01Millimeter mm 0.001Micrometer µm 0.000001
Converting with Metric Units
Covert 0.248 km to centimeters:
0.248 km
Conversion Factors:• 1 Kilometer = 1000 meters• 1 meter = 100 centimeters
Converting with Metric Units
Covert 0.248 km to centimeters:
0.248 km1 km
1000 m
Conversion Factors:• 1 Kilometer = 1000 meters• 1 meter = 100 centimeters
Converting with Metric Units
Convert 0.248 km to centimeters:
0.248 km1 km
1000 m1m
100 cm
Conversion Factors:• 1 Kilometer = 1000 meters• 1 meter = 100 centimeters
Converting with Metric Units
Convert 0.248 km to centimeters:
0.248 km1 km
1000 m1m
100 cm
= (0.248 * 1000 * 100) / 1
= 24,800 centimeters
Much Easier!