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Molar Mass/The Mole

Molar Mass/The Mole. Lesson Plan. Outcomes: 323-1, 323-10. Mass/Molar Mass (Definitions) Avogadro’s Number The Mole. Gram Formula Mass/ Molar Mass. The gram atomic mass of an element is the mass of one mole of those atoms. Example: GAM of 1 mole of AL is 27g.

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Molar Mass/The Mole

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  1. Molar Mass/The Mole

  2. Lesson Plan • Outcomes: 323-1, 323-10. • Mass/Molar Mass (Definitions) • Avogadro’s Number • The Mole

  3. Gram Formula Mass/ Molar Mass • The gram atomic mass of an element is the mass of one mole of those atoms. Example: GAM of 1 mole of AL is 27g. • Therefore: Atomic mass(amu)=Gam(g) • The gram formula mass is the mass of 1 mole of an ionic compound. Ex.KI has a formula mass of 166 amu and a gram formula mass of 166g.

  4. Gram Formula Mass/ Molar Mass • The gram molecular mass is the mass of 1 mole of a molecular compound.Ex. SO3 has an atomic mass of 80.1(amu) and a gmm of 80.1 g. • Example: What is the gmm of hydrogen peroxide?What is the formula for hydrogen peroxide?

  5. Gram Formula Mass/ Molar Mass • Hydrogen has a atomic mass of 1amu so its gam is 1g.Oxygen has an atomic mass of 16amu and an gam of 16g. • We have 2 oxygen an 2 hydrogen atoms in each hydrogen peroxide molecule. 2(16g)+2(1g)= 34g • The gram molecular mass of hydrogen peroxide is 34g.

  6. Concept Map

  7. Homework Assignment

  8. The Mole

  9. Matter is made up of different kinds of particles. • Substances commonly exist as either atoms, ions or molecules, which are then representative particles of that substance.Ex. Iron is found as iron atoms so the atom is its representative particle.

  10. Because substances are made up of particles, one way to measure the amount of a substance is to measure the # of representative particles • This can be very difficult because atoms, ions and molecules are very small.

  11. We can count the particles if we introduce a term that represents a certain number.Ex. we can count eggs by the dozen instead of individually.

  12. One atom of 12C has a mass of 12 amu. This is the definition of the atomic mass unit (amu) • A 12 gram sample of 12C contains one mole of 12C atoms. This is the definition of a mole. • If X is the AW of a element, then X grams of the element will contain 1 mole of atoms • If M is the molecular weight of a compound, then M grams of the compound contains 1 mole of molecules

  13. If F is the formula weight of NaCl, then F grams will contains 1 mole of Na+ ions and one mole of Cl– ions. • If G is the formula weight of CaF2, then G grams will contains 1 mole of Ca2+ ions and two moles of F – ions. The abbreviation for mole is mol Why do we need a 3-letter abbreviation for a 4-letter word!!

  14. Avogadro’s Number The number 6.02  1023 is also called Avogadro’s number in honour of the work of Lorenzo Romano Amadeo Carlo Avogadro di Quaregua e di Cerretto

  15. Molar Mass • The molar mass (in grams) of any substance numerically equals its formula weight (in amu). This is a definition. • The AW of Fe is 55.85 (amu); the molar mass of Fe is 55.85 grams. • The MW of CO2 is 44.01 (amu); the molar mass of carbon dioxide is 44.01 grams • The AW of K is 39.1 (amu); the molar mass of K+ ion is 39.1 grams.

  16. The Mole • The term we have chosen to help in counting particles is the MOLE. • One mole of a substance stands for 6.02x1023 representative particles of that substance.

  17. What is a mole? • It is the quantity of matter that contains an Avogadro number of particles. 1 mole of Fe atoms = 6.02  1023 Fe atoms 1 mole of CO2 molecules = 6.02  1023 CO2 molecules 1 mole of Na+ ions = 6.02  1023 Na+ ions OR • It is the mass in grams equal to the formula weight of the substance 1 mole of Fe = 1 molar mass Fe = 55.85 g 1 mole of CO2 = 1 molar mass of CO2 = 44.01 g 1 mole of NaCl = 1 molar mass of NaCl =58.44 g

  18. The Mole • Interesting Fact • One mole of particles is roughly the number of grains of sand on all the world’s beaches combined.

  19. The Mole • Example Problem #1 • How many moles of magnesium is 3.01x1022 of atoms of magnesium? • 1 mole = 6.02x1023 atoms of magnesium so, • 3.01x1022÷6.02x1023= .0500 or 5.00x10-2moles

  20. The Mole • Example Problem #2 • How many molecules are there in 4.00mol of glucose,C6H12O6? • Answer. 4.00 mole C6H12O6 × 6.02x1023 molecules of C6H12O6 = 2.41×1024 molecules of glucose.

  21. The Mole: Concept Map

  22. Assignment

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