 # Measurement in Chemistry

## Presentation on theme: "Measurement in Chemistry"— Presentation transcript:

Measurement in Chemistry
SI (Metric System) Units Prefixes Factor Label Method Equipment Using density for identification and applications

2. Measurement in Chemistry
Measurements in chemistry always require a ________________ & a ________________. NO ___________________ numbers! We use the International System (SI), which is similar to the metric system:

SI Units Quantity Common unit Measurement Equipment Mass Length Time
Temperature

SI Temperature: Celsius or Kelvin

SI Units Quantity Common Unit Measurement Equipment
Amount of Substance Energy Volume of a Liquid Volume of a Solid

Small and large units Metric System: Similar system but using prefixes
Everyday units (English System) Length Paperclip: Laptop Whiteboard Sandy Porter Road Metric System: Similar system but using prefixes

Small and large measurements
SI System: Based on Powers of Ten

Important SI Prefixes Kilo- k Hecto h Deka- da Base Decid Centi- c
Milli- m 1000 100 10 1 0.1 0.01 0.001 10³ 10² 10¹ 10° 10⁻¹ 10⁻² 10⁻³ 1 meter 1 Liter 1 gram

Equivalent amounts - Memorize!
1 kilometer (_____) = _______ meters 1 hectometer ( ) = ________ meters 1 dekameters ( ) = ________ meters 1 meter = ________ decimeters 1 meter = ________ centimeters 1 meter = ________ millimeter

Memory tool: King Henry Died by Drinking Chocolate Milk

Measurements in chemistry calculations must have the same ____and ______.
To covert: Given Quantity x Conversion Factor = Unknown (or desired) Quantity A known beginning= A desired end= A connecting path=

Factor Label Method Please note: There are other ways to do the metric conversions. However, the following method will be used in chemistry to help prepare for the more difficult mole calculations, which will be in the next unit. Use the other methods to check your answers.

The most important mathematical process in chemistry!
Factor Label Method The most important mathematical process in chemistry! A known beginning = GIVEN A desired end= UNKNOWN A connecting path = CONVERSION FACTOR

Conversion Factor Uses equal quantities 60 seconds = 1 minute
1 km = 1000 meters Conversion factors can be written as ratios Ratios are written as “tops or bottoms” depending on the units to be cancelled.

Example: How many centimeters are in 6.4 meters?

1. How many grams are in 463 kilograms? Given: Unknown:
Example Problems: Given quantity & unit x Unknown unit = Unknown quantity & unit Given unit 1. How many grams are in 463 kilograms? Given: Unknown: Conversion factor: Solve:

2. How many milliliters are in 2.5 liters? Given: Unknown:
Example Problems: Given quantity & unit x Unknown unit = Unknown quantity & unit Given unit 2. How many milliliters are in 2.5 liters? Given: Unknown: Conversion factor: Solve:

3. How many meter(s) are equal to 16 centimeters? Given: Unknown:
Example Problems: Given quantity & unit x Unknown unit = Unknown quantity & unit Given unit 3. How many meter(s) are equal to 16 centimeters? Given: Unknown: Conversion factor: Solve:

Factor Label - Multiple steps example
Calculate the number of seconds in one day. 60 seconds = 1 minute 60 minutes = 1 hour 24 hours = 1 day Given Desired = sec 1 day hr. 60 min. 60 sec = 1 day hr min.

If you are changing prefixes for a measurement:
Size of the number (quantity) Small Big S ↔ B Larger Prefix for the Unit Unit Prefix Smaller Prefix for the Unit Double check your answers!

SI Prefixes