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Unit 5 - Counting Particles

Unit 5 - Counting Particles. Chem Catalyst – 3/24. Up front is a garbage bag full of Styrofoam peanuts. We want to count how many peanuts are in the bag. Describe a few ways you could determine how many peanuts were in the bag. Chem Catalyst. If you have the following relationships:

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Unit 5 - Counting Particles

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  1. Unit 5 - Counting Particles

  2. Chem Catalyst – 3/24 • Up front is a garbage bag full of Styrofoam peanuts. We want to count how many peanuts are in the bag. Describe a few ways you could determine how many peanuts were in the bag.

  3. Chem Catalyst • If you have the following relationships: • 1 box of nails = 100 pieces of nails • 25 pieces of nails = 15.0 g of nails • 1000 g = 1 kg, 1 kg = 2.20 lbs • How many pounds of nails are there in 14,000 pieces of nails?

  4. What do these pictures have in common?

  5. Think back to yesterday’s class • What counting units did we use in the lab yesterday? • What are some other common counting units? • Dozen, gross, score • In chemistry, the “mole” is a counting unit.

  6. Counting units • 1 dozen = 12 particles of something • 1 gross = 144 particles of something • 1 score = 20 particles of something • 1 mole = 6.02 x 1023 particles of something • “Avagadro’s number”, NA

  7. The Mole – Avogadro’s Number6.02 x 1023 • Amedeo Avogadro came up with “the mole” as a counting unit in chemistry. • The mole is very useful for determining the number of particles in a sample of a certain substance, like titanium, gold, table salt, etc. • Doing experiments, Avogadro found that 12 grams of carbon = 6.02 x 1023 atoms of carbon.

  8. How big is the number 6.02 x 1023? 602,000,000,000,000,000,000,000 written in standard format • 1 mole of rice = cover all land 75 ft. thick! • 1 mole marshmallows = cover U.S. in 650 miles of marshmallows! • 1 mole of basketballs = fill a ball bag the size of earth • If every living person on earth started counting one paperclip each second, it would take 4 million years to reach 6.02 x 1023 paperclips!

  9. Count how many dozen paperclips are on the next slide

  10. How many paperclips would be in 2 moles of paperclips?

  11. Just like we can have 1/2 of a dozen:

  12. How many particles would be in 0.5 moles?

  13. Chem Catalyst All problems below are about methane,CH4. - How many molecules (particles) of methane are in 1 mole? • In one molecule of methane, how many atoms of hydrogen do you have? • In 2.0 moles of methane, how many molecules (particles) of methane do you have? • In 2.0 moles of methane, how many total atoms of H and C do you have?

  14. The car as a molecular formula • 1 car = __ Tires, __Windshield Wipers and __Steering Wheel • As a formula,1 car = T W S If I had 3 cars……. How many tires would I have? How many wipers? How many steering wheels?

  15. Recall our car example • 1 car = T4W2S If I had 1 dozen cars, how many tires would I have? Wipers? Steering wheels? How many dozen tires would I have? How many dozen wipers? How many dozen steering wheels?

  16. Recall our car example • 1 car = T4W2S If I had 1 gross of cars, how many tires would I have? Wipers? Steering wheels? How many gross of tires would I have? How many gross of wipers? How many gross of steering wheels?

  17. Chem Catalyst • How many moles of hydrogen are there in one mole of water? • How many moles of oxygen are there in one mole of water? • How much do you think one mole of water molecules is? 1 liter? 1 mL? 1000 L?

  18. Paperclip counting challenge

  19. Chem Catalyst Imagine you have 4 moles of hydrogen (H2) gas and 3 moles of H2O. • How many grams of hydrogen gas would you have? How many molecules of hydrogen gas would you have? How many atoms of hydrogen would you have? • How many grams of water would you have? How many molecules of water would you have? How many H and O atoms would you have?

  20. Molar Mass Worksheet

  21. Chem Catalyst • What is the molar mass of ammonia, NH3? Write the molar mass as an equality. 1 mole of NH3 = ___ grams of NH3 • ESTIMATE – How many moles of NH3 do you think you would have if you had 50 grams of NH3? • GET A PERIODIC TABLE AND CALCULATOR!

  22. Gram-Mole and Mole Gram Conversion Worksheet

  23. Re-work problem assignment • Test Wednesday • More than a trillion: 2, 3, 4 • Moles within moles: 9a-c, 11 • Molar mass: 5a-c • Gram-Mole conversions: 1, 2, 8, 9, 10

  24. ChemCatalyst 1.) Find the molar mass of aspartame and write it as an equality. 1 mole of aspartame = ____g of aspartame 2.) If you have 256 grams of aspartame, how many moles would that be?

  25. Which can has more molecules? • Regular soda: 40 g of fructose. • Diet soda: 0.225 g of aspartame • Use the factor label method to calculate the number of moles of each molecule in the two cans.

  26. Chem Catalyst • What is the molar mass of copper (II) chloride, CuCl2? Write your answer as an equality. • How many grams are in 3.5 moles of copper (II) chloride? • How many moles are in 40 grams of copper (II) chloride? • If you have 0.81 moles of CuCl2,how many molecules (particles) of CuCl2 would you have?

  27. Nail Lab – Day 1 + 1.) Wear goggles! 2.) Label beaker with group names using marker provided. 3.) Weigh empty beaker to nearest 0.01g 4.) Mr. Fritz will pour 50mL of CuCl2 solution into your beaker. 5.) Weigh 2 nails to nearest 0.01g 6.) Make observations about nails and CuCl2 solution BEFORE putting nails in. 7.) Put nails in copper chloride. Make observations after putting nails in.

  28. Chem Catalyst • What is the molar mass of calcium bromide, CaBr2? Write your answer as an equality. 1 mole of CaBr2 = ___ grams of CaBr2 • How many moles are in 30 grams of calcium bromide? • How many molecules (particles) are in that many moles of CaBr2? *Hint = use Avagadro’s Number!

  29. Nail Lab – Day 2 + = ? 1.) Wear goggles! 2.) Remove nails with tweezers 3.) Scrape precipitate from the nail into your beaker with a plastic spoon. 4.) Dry nails with paper towel. 5.) Pour (decant) the solution in the waste beaker at your lab table. DON’T POUR OUT COPPER PRECIPITATE! 6.) Rinse copper twice with water, once with 1M HCl, once again with water. 7.) Weigh dry nails, record data, throw nails away.

  30. Chem Catalyst • Lead (II) sulfate, PbSO4, was used as a pigment in paints. How many moles of lead sulfate are in 50.0 g of lead(II) sulfate? How many atoms of oxygen are present?

  31. Chem Catalyst • What do you think is happening to the copper and the iron in the nail lab?

  32. Calculations • Do the calculations. Then compare to Dr. Chen’s numbers. • Mass of iron nails before = 5.12 g • Mass of iron nails after = 2.23 g • Mass of copper powder = 2.55 g

  33. Chem Catalyst – 3/16/09 Below is a chemical “sentence” describing the formation of a very toxic substance, hydrogen cyanide. NaCN (s) + HCl (aq) → NaCl (aq) + HCN (g) What kinds of information does this chemical notation contain? List at least four pieces of information contained in this chemical notation.

  34. Announcements • MOLE TEST – If you have not taken it yet, you MUST come to my flex tomorrow to complete it – or come before/after school. • RETAKES – You may retake the back portion of the exam for up to 80% credit by the end of this week. Flex, before school, or after. LOOKING AHEAD…….. • NO SCHOOL – NEXT Monday, 3/23 – PD Teachers • PT Conferences – NEXT Thursday, 3/26 • End of Marking Period – 4/3 – only 3 weeks away! • SPRING BREAK – 4/10-20 

  35. Making Sense Brownish-liquid CuCl2(aq) + Fe(s) ----> FeCl2(aq) + Cu(s) Reactants: Products:

  36. CuCl2(aq) + Fe(s) ----> FeCl2(aq) + Cu(s)

  37. Chem Catalyst – 3/17/09 Consider the following reaction: AgNO3 (aq) + KCl (aq) → KNO3 (aq) + AgCl (s) • What do you expect to observe if you carried out the reaction? • Translate the above chemical equation into writing, describing what is taking place.

  38. Making Sense • What are some observations you made? • What types of observations are asociated with the changes that took place? (aq, s, g) • Why do you think there are two equations for some of the procedures?

  39. Chem Catalyst – 3/18/09 • The following two equations both describe what happens when dry ice is placed in water: CO2 (s) → CO2 (g) CO2 (s) + H2O (l) → H2CO3 (aq) • What differences do you see in these two equations? • Why do you think two equations are needed to describe what happens?

  40. Making Sense • Physical Changes: Changes in the appearance or form of a substance. Ex: CO2 (s) → CO2 (g) H2O (l) → H2O (g) H2O (s) → H2O (l) • Chemical changes: New substances with new properties are produced. Ex: CO2 (s) + H2O (l) → H2CO3 (aq) AgNO3(aq) + KCl(aq) → KNO3(aq) + AgCl (s)

  41. Is dissolving a chemical change or a physical change? Demonstration: CoCl2(s) --> CoCl2(aq) Often written as: CoCl2(s) -->

  42. Check-In • Does the following chemical equation describe a physical change or a chemical change? Explain how you can tell. C17H17O3N(s) + 2C4H6O3(l) → C21H21O5N(s) + 2 C2H4O2(l)

  43. Chem Catalyst – 3/19/09 • Consider the following reactions: 1.) CaCO3 (aq) --> CaO (aq) + CO2 (g) 2.) CO2 (g) + NaOH (aq) --> NaHCO3 (aq) • How are these two reactions different? (Look at the whole reaction) • How would you describe, in words, what happens to the reactant molecules in each case?

  44. TOXINS – What’s your reaction? • We can study chemical reactions by learning about how toxic substances react with your body. • Ex: Phosgene, COCl2 (g) – Damages eyes, nose, throat, lungs Verbal description: Phosgene gas reacts with water (tears, saliva, mucuous) to produce aqueous hydrochloric acid and carbon dioxide gas. COCl2 (g) + H2O (l) --> 2 HCl (aq) + CO2 (g) • Used as a biological weapon in World War I

  45. Chem Catalyst – 3/24/09 • Consider the following reaction. Na2CO3 (aq) + CaCl2 (aq) --> NaCl (aq) + CaCO3 (s) • Describe what you will observe when Na2CO3 (aq) and CaCl2 (aq) are mixed. • Will the mass increase, decrease, or stay the same after mixing? Explain.

  46. Results from Lab 1.) NaCl (s) --> NaCl (aq) • Did the mass change for this reaction? • Why or why not?

  47. Results From Lab • Na2CO3 (aq) + CaCl2 (aq) --> NaCl (aq) + CaCO3 (s) • Did the mass change for this reaction? • Why or why not?

  48. Results From Lab • Na2CO3 (aq) + C2H4O2 (aq) --> • NaC2H3O2 (aq) + H2O (l) + CO2 (g) • Did the mass change for this reaction? • Why or why not? • Do gases have mass?

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