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Introduction to the Mole

Introduction to the Mole. Counting Atoms. A special unit used by chemists to express amounts of particles such as atoms , molecules , or ions . The SI unit for amount of substance Abbreviated mol A counting unit , similar to a dozen. The Mole.

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Introduction to the Mole

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  1. Introduction to the Mole Counting Atoms

  2. A special unit used by chemists to express amounts of particles such as atoms, molecules, or ions. • The SI unit for amount of substance • Abbreviated mol • A counting unit, similar to a dozen The Mole

  3. The number of particles in a mole has been experimentally determined in a number of ways. • The best modern value is 6.0221415 x 1023 (we will use 6.022 x 1023) • Amedeo Avogadro’s ideas were extremely important in determining the relationship between mass and numbers of atoms Avogadro’s Number

  4. Imagine you have a mole of pennies to count • You employ everyone in the world (7billion people) to help you count. • Everyone will count 24 hours a day, seven days a week. • Each person counts 1 penny per second • 7 billion pennies are counted each second. • 25.2 trillion pennies are counted each hour. • 600 trillion pennies are counted each day. • It would take almost one billion days to count to a mole (6.022 x 1023). • In other words, it would take almost 3 million years, with everyone in the world counting! Just How Big is a Mole?

  5. If you laid out a mole of pennies end to end they would extend to the moon and back 7 times. • A mole of aluminum cans would cover the Earth's surface (land and oceans) over 200 miles deep. • A mole of chocolate chips would cover the earth over 500 feet deep. Just How Big is a Mole?

  6. If you had a mole of pennies in your bank account? • With a mole of water? What Would You Do?

  7. The Mole Concept Video Clip

  8. The mole is used in chemistry primarily to make calculations easier. • Since atoms are so small, most calculations would involve incredibly large numbers, therefore the mole is used. • We will use the conversion factor method that was introduced in the beginning of the year. (1 mole = 6.022 x 1023 atoms) Calculations Involving the Mole

  9. Start with • Set up conversion factor so that the given units cancel • Solve • Multiply numerators • Multiply denominators • Divide • Include final units Review of Conversion Factors

  10. How many moles are in 3.01 x 1023 atoms of silver? • = = 0.500 mol Ag • Significant Figures (Start with 3, end with 3) • Calculator hints: USE PARENTHESIS E = x 10 1 mol Ag atoms Ag 6.022 x 1023 Sample Problem 1

  11. How many atoms of aluminum are in 2.75 moles of aluminum? • = 1.66E24 = 1.66 x 1024 atoms Al • Significant Figures (Start with 3, end with 3) • Calculator hints: USE PARENTHESIS E = x10 atoms Al 6.022 x 1023 1 mol Al Sample Problem 2

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