The Mole , Ch. 10 You need a calculator from this chapter on.

1. The Mole, Ch. 10You need a calculator from this chapter on.

3. *The mole was invented as a way to describe number of atoms.

4. *1 mole = 6.02 x 1023 things. • 602,000,000,000,000,000,000,000 things.

6. What if you had a mole of $1 bills?

7. In a mole of water, there are 6.02 x 1023 molecules of H2O. • Pass around 1 mole of water.

8. *Converting moles to # of particles • Convert 3 moles of aluminum to number of atoms of aluminum. • Convert 7 moles of methane to molecules of methane.

9. *Molar Mass • One mole of an atom will weigh ___ grams (shown on the periodic table).

10. *Convert moles to grams • Mg. 1 mole  ? grams • 6.94 grams

11. 3 moles Be  ? grams • 27 grams.

12. 2.5 x 1022 atoms of Na  grams Na? • .96 grams

13. 3 moles of CH4 to grams? • 48 grams.

14. 4 moles of HF to grams? • 80 grams

15. Try it: • 6 moles of H2O to grams. • 126 g of NaF to moles. • 108 grams, 3 moles

16. Molar mass of Uranium a ball of uranium with a radius of 1.3 inches weighs a pound.

17. *A mole of any gas takes up 22.4 L (at STP). This is Avogadro’s Hypothesis. • This is like a cube with sides of 28.2 cm.

19. One mole of He, H, O, N, etc. will all take up 22.4 L. • Question: How many He atoms are there in 22.4 L? • Question: How many H2 molecules are there in 22.4 L?

20. How many moles of O2 in 44.8 liters of O2?

21. How many L in 4 moles of N2? • 89.6 L

22. STP 0 C, pressure = 1 atm (101.3 kPa)

23. Gas Density: • Often is measured in g/L. • What is the density of H2 gas at STP? • .089 g/L

24. Gas density

25. Page 303, roadmap. • Try: 55 E23 particles of He to volume of gas. Try: 55 E23 particles of He to grams of gas.

26. Be able to solve mole problems. • Compare a mole of eggs to a dozen eggs. • What is a mole useful for?

27. *Gas density to molar mass. • Exp: 2.86 g/L.

28. Percent Composition • Is the percent by mass of each element in the compound.

31. *Percent Composition from mass data: • 5.4 g of oxygen and 8.2 g of magnesium in a 13.6 gram compound. • 60.3% Mg, 39.7% O

32. *Percent composition from the chemical formula Find the amount of grams of each element in 1 mole of the compound, then find the %. • C3H8 • 81.8% C, 18% H

33. How many grams of O are present in 36 grams of H2O? • 32 grams O

34. *Empirical formula: Expresses the atoms in their lowest ratio. • *Molecular formula: Expresses the atoms in their actual abundance. • Exp: H2O2 HO

35. *Determining Empirical Formula: • 25.9% N • 74.1 % O • Assume 100 g of the compound, find the # of moles, then find the whole number ratio. • Answer = 2 mol N, 5 mol O

36. The molecular formula is always a whole number multiple of the empirical formula.

37. Empirical formula to Molecular formula If the empirical formula is CH4N and the molecular molar mass is 60 g/mol, what is the molecular formula? • C2H8N2

38. Gas Chromotography

39. Uses for Gas Chromotography

40. The end

41. Assignment • Draw and explain with words: • If you could have a mole of anything, what would you want and why? • Can be creative and funny.