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10-1: THE MOLE

10-1: THE MOLE. You will need your calculator EVERY DAY!!!!!!!!!!!. The Mole. 1. Avogadro’s Number (aka the MOLE): A MOLE of something (cars, bananas, atoms, molecules, people) is 6.02 x 10 23 This concept is similar to the idea of a “dozen” being equal to 12 things (eggs, cookies, etc )

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10-1: THE MOLE

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  1. 10-1: THE MOLE You will need your calculator EVERY DAY!!!!!!!!!!!

  2. The Mole 1. Avogadro’s Number (aka the MOLE): • A MOLE of something(cars, bananas, atoms, molecules, people)is 6.02 x 1023 • This concept is similar to the idea of a “dozen” being equal to 12 things (eggs, cookies, etc) • Because atoms are so small, it takes a huge number of them to make up a visible amount. The mole allows us to talk about the number of atoms in a sample we have.

  3. 2. Where did chemists come up with that random number? • Named after the man who founded it (Avogadro) • In carbon-12 (i.e. C with 6 protons and 6 neutrons, which has an atomic mass of 12 amu), there are 6.02 x 1023 C atoms in 12 grams. • Said another way, one mole of C atoms is 12 grams • The mole allowed chemists to talk about how much of an element they have in grams

  4. 3. How big is Avogadro’s the number? Why is it so big? • If you stacked a mole of sheets of paper on top of each other, the stack would reach beyond the solar system • This number is so large so we can reasonably talk about a HUGE amount of really tiny atoms

  5. Working with the mole… • First, let’s look at something familiar… 4. Let’s say I have a dozen bikes. How many wheels do I have? How many dozen wheels do I have? 5. Let’s say I have one mole of bikes. How many moles of wheels do I have? 6.How many wheels do I have in 1 mole of bikes?

  6. ANSWERS • First, let’s look at something familiar… 4. Let’s say I have a dozen bikes. How many wheels do I have? How many dozen wheels do I have? 2 dozen wheels or 24 wheels 5. Let’s say I have one mole of bikes. How many moles of wheels do I have? 2 moles of wheels 6.How many wheels do I have in 1 mole of bikes? 2 moles wheels x (6.02 x 1023) = 1.2 x 1024 1 mole

  7. Now let’s talk about atoms… A: How many atoms/ions are in a compound? • Look at the subscripts and add the total number of elements together. If necessary, multiply by the total # of ions/elements. • Example: How many ions are there in the compound CaCl2? • How many Cl ions are in the compound? • If I have 12 CaCl2 compounds, how many Cl ions do I have?

  8. Example: How many ions are there in the compound CaCl2? Ca + Cl + Cl = 3 • How many Cl ions are in the compound? Cl + Cl = 2 • If I have 12 CaCl2 compounds, how many Cl ions do I have? CaCl2 CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2CaCl2 OR 12 X 2 = 24 Cl atoms

  9. B. How many moles of each type of atom/ion do I have? • Multiply the number of moles by the subscript • Example: How many moles of Cl are in 5 moles of the compound CaCl2? • How many moles of Cl atoms are in ONE mole? • Multiply by how many moles you have:

  10. B. How many moles of each type of atom/ion do I have? • Example: How many moles of Cl are in 5 moles of the compound CaCl2? • How many MOLES of Cl atoms are in ONE mole? 2 atoms per compound  2 moles Cl per mole • Multiply by how many moles you have: 10 moles Cl

  11. C. How many atoms/ions do I have? Multiply the number of MOLES of the atom by Avogadro’s number. • Example: How many ions of Cl are in 5 moles of compound CaCl2? • First find the total # of moles of Cl: • Use Avogadro’s number as a conversion factor: 6.02 x 1023 1 mole (cancel units you don’t want)

  12. C. How many atoms/ions do I have? Multiply the number of MOLES of the atom by Avogadro’s number. • Example: How many ions of Cl are in 5 moles of compound CaCl2? • First find the total # of moles of Cl: 10 moles Cl • Use Avogadro’s number as a conversion factor: 6.02 x 1023 1 mole (cancel units you don’t want) • 10 moles Cl x6.02 x 1023 = 6.02 x 1024Cl atoms 1 mole

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