Measurement & Unit ConversionsReading Ch 2.1-2.4

(pp. 31-61)Why would chemistry students be interested

in unit conversions?• Measurements- involve a number & a unit• Different measurement systems

-English- (lb.,mile, inch, cup, gallon, etc.)

-Metric- (gram, meter, liter, etc.)

Unit conversions, con’t

• Use a T-chart to solve unit conversions- this is a simple method to use equalities to cancel out unwanted units.

• Equalities represent 2 numerical values and their units that are equal to each other and therefore be converted.

1 mile = 5280 ft.

T-Chart Conversion Problems1. How many inches in 2.1 miles?2. How many liters in 68 gallons? (HINT: 1 liter

= 1.0567 quarts)3. How many seconds in 4.5 score of years?(1

score = 20 years)4. How many grams in 0.95 pounds of

hamburger?(454 g=1 lb.)5. If there are 8 fluid ounces in a cup, how many

fluid ounces in 4.9 gallon?

Metric System (aka- SI System)**Units are made of prefix + base unit

• Base units• Length- meter• Mass- gram• Volume-liter• Time- seconds• Amount of substance-mole

Prefixes- are added to base units to change the value

• Less than 1• Deci- 10-1

• Centi- 10-2

• Milli- 10-3

• Micro- 10-6

• Nano- 10-9

• Greater than 1• Deka- 101

• Hecto- 102

• Kilo- 103

• Mega- 106

• Giga- 109

Examples-

• Kilogram = 1000 grams or 103 grams• Millisecond = .001 second or 10-3 second

• What would the unit be for 100 liters?• Answer: Hectoliter or 102 liters

• What would the unit be for 0.01 meter?• Answer: Centimeter or 10-2 meter

Conversions w/ Metric units?

1. Use t-charts.

2. Use equalities

3. Solve for wanted unit.

Metric Conversions

Ex. Convert 40 kilograms to grams.

40 kg 1000 grams

1 kg

= 40,000 grams

Practice with Metric Conversions

1. Convert 6.5 kg to mg

2. Convert 870 dam to cm.

3. Convert 7.80 hL to mL.

Metric Equivalents** the base units (in bold) are interchangeable

• 1,000,000,000 nanometers = 1 meter• 1,000,000 micrometers = 1 meter

• 1000 millimeters = 1 meter• 100 centimeters = 1 meter• 10 decimeters = 1 meter

Metric Equivalents con’t

• 10 meters = 1 dekameter

• 100 meters = 1 hectometer

• 1000 meters = 1 kilometer

• 1,000,000 meters = 1 megameter

• 1,000,000,000 meters = 1 gigameter