1 / 88

Chapter 10

Stoichiometry and The Mole. Chapter 10. 6.02 X 10 23.   Stoichiometry: What is it?. The word stoichiometry derives from two Greek words: stoicheion (meaning "element") and metron (meaning "measure").

euclid
Download Presentation

Chapter 10

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Stoichiometry and The Mole Chapter 10 6.02 X 1023

  2.   Stoichiometry: What is it? • The word stoichiometryderives from two Greek words: stoicheion(meaning "element") and metron(meaning "measure"). • Stoichiometry deals with calculations about the masses (sometimes volumes) of reactants and products involved in a chemical reaction. • It is a very mathematical part of chemistry, so be prepared for lots of calculator use.

  3. Measuring Matter • What do the terms ream, gross, dozen, pair have in common? • They are all counting units, designed to make counting objects easier. • Today, we will look at a counting unit for chemistry.

  4. Counting Particles • Chemists need a convenient method for counting • atoms, molecules, and formula units in a sample of substance. • This counting unit is called the Mole. • What is a Mole???? • It’s Just like a Dozen only bigger.

  5. A mole is… • SI base unit used to measure the amount of substance. • It is the number of carbon atoms in exactly 12 grams of Carbon-12. • Has a value of 6.02 x 1023 • Called Avogadro’s Number • Named after Amedeo Avogadro • Commonly abbreviated mol. • Just like a dozen only bigger

  6. How Big is a Mole ? 6.02 X 1023 • Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles. • If you had Avogadro's number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles. • If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole. 6.02 X 1023 6.02 X 1023 6.02 X 1023 6.02 X 1023

  7. Launch Lab • To appreciate the magnitude of the mole • To practice dimensional analysis

  8. Representative Particles 6.02 X 1023 • Molecules for covalently bonded substances • Ex. A water molecule • Formula Units for Ionic Substances • Ex. A formula unit of sodium chloride • Atoms for elements • Ex. An atom of sulfur

  9. Converting Moles and Particles • 1 mole = 6.02 x 1023 particles • Used to convert • Moles to Particles • Particles to Moles

  10. Particles to Moles • How many moles of methanol, CH3OH, are there in 6.53 x 1023 molecules of methanol?

  11. Avogadro’s Number as Conversion Factor 6.02 x 1023 particles 1 mole or 1 mole 6.02 x 1023 particles Note that a particle could be an atom OR a molecule!

  12. Moles to Particles A sample containing 0.75 moles of CO2 would contain how many molecules?

  13. Examples How many Fe atoms would be present in 1.27 moles of Fe?

  14. Example 4.47 x 1023 molecules of C6H12O6 would be how many moles?

  15. Example Calculate the number of moles contained in 4.50 x 10 24 atoms of zinc.

  16. Example • How many molecules in 2.8 moles of water?

  17. Oranges vs Grapes • Draw a bowl with one dozen grapes in it. • Draw a bowl with a dozen oranges in it. • Compare the masses. • Why are they not the same?

  18. Copper Vs Aluminum • Draw a circle. • Label it as 1 mole of copper atoms. • Draw another circle. • Label as 1 mole of aluminum atoms. • How many atoms is one mole? Label. • Which weighs more? • Look up masses on periodic table.

  19. Molar Mass • The mass of one mole of a substance is called "molar mass" • Units g/mol (grams per mole). • Molar mass is the weight in grams of one mole • One mole contains 6.02 x 1023 entities • Therefore, a molar mass is the mass in grams of 6.022 x 1023 entities

  20. Molar Masses • Aluminum • Zinc • Copper • Iron

  21. Just as a dozen oranges would not weigh the same as a dozen grapes… • A mole of copper atoms does not have the same mass as a mole of aluminum atoms. • We know that the relative scale for atomic mass uses the carbon-12 isotope as a standard.

  22. Each atom of carbon-12 has a mass of 12 amu. • The atomic mass on the periodic table are weighted averages of all isotopes. • Since one mole is defined as the number of carbon-12 atoms in exactly 12 grams of C-12. Therefore…

  23. The mass of One Mole of C-12 is 12.0 grams. • Called Molar Mass: the mass in grams of one mole of a pure substance • Example: • An atom of Manganese • Atomic Mass = 54.94 amu • Molar Mass = 54.94 g/mol

  24. 1 mole Ag= 6.02 x 1023 atoms Ag = 107.87 grams Ag 1 mole K = 6.02 x 1023 atoms K = 39.10 grams K 1 mole H2gas = 6.02 x 1023 molecules H2 = 2.02 g H2

  25. Mole to Mass Conversions Calculate the mass in grams of 0.0450 moles of chromium.

  26. Mass to Mole Conversions How many moles of calcium are contained in 525 grams of calcium?

  27. Molar Mass of Compounds • Similar mole-mass, mass-mole conversions can be made for compounds • We must know the Molar Mass for the Compound. • How do we calculate Molar Mass of a Compound?

  28. Chemical Formulas and the Mole • Recall that for CCl2F2 • The subscripts tell us that one molecule of freon contains… • One atom carbon • Two atoms chlorine • 2 atoms fluorine

  29. Suppose you have one mole of freon molecules there would then be • One mole of carbon atoms • Two moles chlorine atoms • Two moles fluorine atoms

  30. What if you have 6 moles of freon? • 6 moles of CCl2F2 contains • 6 moles carbon atoms • 12 moles chlorine atoms • 12 moles fluorine atoms

  31. Molar Mass of Molecules and Compounds Mass in grams of 1 mole equal numerically to the sum of the atomic masses 1 mole of CaCl2 1 mole Ca x 40.1 g/mol + 2 moles Cl x 35.5 g/mol= 70.9 g/mol = 111.1 g/mol CaCl2

  32. The Molar Mass Example Calculate the molar mass of K2CrO4

  33. Example Calculate the Molar Mass of K2O

  34. Learning Check Prozac, C17H18F3NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. Find its molar mass.

  35. Converting Mass to Moles How many moles are represented by 16.0 g of ethanol, C2H5OH ?

  36. Converting Mass to Moles How many moles of NaCl are in 16.0 grams of NaCl?

  37. Mass to Moles How many moles of potassium hydroxide, KOH are in 40.6 g?

  38. Mass to Moles How many moles of glucose, C6H12O6 are in 27.2 g of glucose?

  39. Moles to Mass How many grams in 0.158 moles of KMnO4?

  40. Moles to Mass How many grams in 1.2 moles of H2O?

  41. Moles to Mass • How many grams in 0.87 moles of H2O2?

  42. Moles to Mass How many grams in 0.43 moles of C6H12O6?

  43. Calculations with Molar Mass X molar mass Grams Moles Moles Grams divide by molar mass

  44. Learning Check! The artificial sweetener aspartame (Nutra-Sweet) formula C14H18N2O5 is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame?

  45. Atoms/Molecules and Grams 6.02 X 1023 particles = 1 mole AND 1 mole = molar mass (grams) • You can convert atoms/molecules to moles and then moles to grams! (Two step process) • You can’t go directly from atoms to grams!!!! You MUST go thru MOLES. • That’s like asking 2 dozen cookies weigh how many ounces if 1 cookie weighs 4 oz? You have to convert to dozen first!

  46. Molecules to Grams How many grams of glucose are in 6.63 x 1023 molecules of glucose, C6H12O6?

  47. Grams to Molecules Determine the number of molecules found in a 12.4 g sample of H2SO4.

  48. Molecules to grams 3.14 x 1023 molecules of CO2 are produced in a chemical reaction. How much would the sample weigh in grams?

  49. Grams to atoms How many atoms are in a 39.8 g sample of Fe?

  50. Mole Road Map Everything must go through Moles!!!!

More Related