Chem 122: Chapter 1 Sec. 3-4/ Chapter 2 Sec. 2-5

What is the SI unit for mass?

kilogram (kg) * the only base unit whose name has a prefix

In chemistry what non-SI units do we typically use for volume?

liter (L) milliliter (mL)

Remember to always include _____ for all calculations in Chem 122.

unit EX: a person's height is 5 feet, 10 inches" not "5,10"

A cheetah, which is one of the fastest animals on the Earth, can cover ground of short distances at 75 miles per hour. How long (in seconds) will it take a cheetah to cover a distance of 300. meters? (1 mile = 1.609 km)

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Conversion factor you choose must cancel all units except those you want in the answer. Provide a simple example.

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Conversion factor you choose must cancel all units except those you want in the answer. Provide an example that involve units raised to a power.

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If we know the Angel Falls in Venezuela is 0.9788 km high, how tall is the waterfall in meters (m)? 1 km = 1000 m

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Sample Problem 1.3: To write your stereo equipment, you need 325 centimeters (cm) of speaker wire that sells for $0.15/ft. How much does the wire cost?

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We use conversion factors to convert from one system of units to another. Like converting between the English (or American) unit system and the International System. Ex: The height of Angel Falls in Venezuela is 3212 ft; what is its height in miles? 1 mi = 5280 ft

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What are all decimal prefixes used with SI units?

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What are the seven fundamental units or base units?

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What is the distance of a 150 mile car trip in feet? 1 mi = 5280 ft

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You can string together several conversion steps. So if we know the Angel Falls in Venezuela is 3212 feet high, how tall is the waterfall in meters (m)? Show your work with several conversions steps strung together. 1 mi = 5280 ft 1.609 km = 1 mi 1 km = 1000 m

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If we know the Angel Falls in Venezuela is 0.6083 miles high, how tall is the waterfall in kilometers (km)? 1.609 km = 1 mi

(See image) * Notice that kilometers are smaller than miles, so this conversion factor gave us an answer with a larger number. (0.9788 is larger than 0.6083)

Dimensional analysis

(also factor-label method) A calculation method in which arithmetic steps are accompanied by canceling units that represent physical dimensions.

Conversion factor you choose must cancel all units except those you want in the answer. Provide an example involving a ratio of units.

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For quantities much smaller or larger that the base unit, we use _______ and _______ .

1.) decimal prefixes 2.) Scientific notation (exponential notation)

Conversion factor

A ratio of equivalent quantities that is equal to 1 and used to express a quantity in different units.

SI Units

A unit composed of one or more of the base units of the System International d'Unites, a revised form of the metric system.

SI system is based on seven fundamental units or base units, each identified with a physical quantity. Define the underlined terms.

A unit that defines the standard for one of the seven physical quantities in the International System of Units (SI).

Derived Units

Any of various combinations of the seven SI base units. Example: the derived unit of speed, meters per second (m/s), is the base unit for length (m) divided by the base unit for time (s).

What is the difference between mass and weight?

Mass is constant because an object's quantity of matter cannot change. EX: a penny on Earth has the same mass it would have it if was on the moon. Weight is variable because it depends on the local gravitational field acting on the object. EX: Because the strength of the gravitational field varies with altitude, you (and other objects) weigh slightly less on a high mountain than at sea level.

What is the SI unit for length?

Meter (m)

Units can be multiplied, divided, and canceled. Provide examples.

Multiplied: A carpet measuring 3 feet by 4 feet (ft) has an area of Area = 3ft x 4 ft = (3 x 4) (ft x ft) = 12 ft ^2 Divided: A car traveling 350 miles (mi) in 7 hours (h) has a speed of Speed = 350 mi = 50 mi 7h 1h (often written 50 mi X h^-1) Canceled: In 3 hours, the car travels a distance of (See image)

Does a sample weighed on laboratory balances in Miami (sea level) and in Denver (about 1.7 km above sea level) give different results?

No, because these balances measure mass, not weight.

What is the SI unit for time?

Seconds (s)

Volume

The amount of space occupied by a sample of matter

Weight

The force that is exerted by a gravitational field on an object and is directly proportional to the object's mass.

Mass

The quantity of matter an object contains. Balances are designed to measure ____.

What is the SI unit of volume? Why?

cubic meter (m^3) Because: Volume = length x width x height (meters x meters x meters = m^3)