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Starter. Retrieve a Unit 6 Mole Review Packet from the front table Recall dimensional analysis… What were some important methods you used? How did you convert your units?. Meet the Mole. Moles. The mole is a unit of measurement used in chemistry.

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  1. Starter • Retrieve a Unit 6 Mole Review Packet from the front table • Recall dimensional analysis… • What were some important methods you used? • How did you convert your units?

  2. Meet the Mole.

  3. Moles • The mole is a unit of measurement used in chemistry. • The unit can be defined in multiple ways. (We’ll learn 3 today.) • In its simplest terms, it represents a specific number. • Dozen = what number? • Pair = what number? • Baker’s dozen = what number? • Mole = 6.022 x 1023

  4. Mole = 6.022x1023 things • Just like a dozen means 12 of anything... 6.022x1023 of anything equals of mole. • Consider the size of 6.022x1023. Is it large or small? • Would you commonly use 6.022x1023 with large things or small things?

  5. Atoms, Elements, & Compounds • In chemistry, we are often dealing with VERY SMALL things. • Atoms are SUBmicroscopic. In order to have an amount large enough with which to really interact, we need quite a few atoms. 6.022x1023 is the number that Amadeo Avogadro chose in his lab using carbon.

  6. Avogadro’s Number • 6.022x1023 • My pet mole is named Avogadro.

  7. Defining the Mole • Counting • Weighing • Amount of Space Needed

  8. Moles & Mass of Compounds • A compound is a collection of atoms. • To calculate the mass of one mole of a compound, you’d need to add up the mass of all the atoms. This is called the MOLAR MASS. • Example: 1 mole CH4 = ______ g CH4 • 1 C = 12.011 g C • 4 H = 4(1.0079 g H) • Total = 16.04 g/mol

  9. Another Molar Mass Example • Calculate the molar mass of sulfur dioxide, a gas produced when sulfur-containing fuels are burned. • SO2 • S = 32.07 g • O = 2(16.00 g) • Total = 64.07 g/mol • Can also be expressed as 1 mol SO2 = 64.07 g

  10. Using Molar Mass • Calculate the molar mass for sodium sulfate, Na2SO4. A sample of sodium sulfate with a mass of 300.0 g represents what number of moles of sodium sulfate? • Identify the given and the unknown. • What is the conversion factor on the mole map? • Set up the calculation.

  11. Finding the Number of Atoms • Aluminum (Al), a metal with a high strength-to-weight ratio and a high resistance to corrosion, is often used for structures such as high-quality bicycle frames. Compute both the number of moles of atoms and the number of atoms in a 10.0-g sample of aluminum. • How many calculations is this prompt asking me to carry out? • Concentrate on one calculation at a time • Continue work on the board.

  12. Finding the Number of Atoms • A silicon chip used in an integrated circuit of a computer has a mass of 5.68 mg. How many silicon (Si) atoms are present in this chip? The average atomic mass for silicon is 28.09 amu.

  13. Finding the Number of Atoms • What if they ask you for the number of atoms of a certain element within the molecule? • You must use a Mole Ratio • Example: • How many O atoms are in 10 grams of water? • How many C atoms are in dicarbontetrahydride?

  14. Molar Volume • If converting between the units of moles and liters of a gas, what conversion factor is needed? • 1 mole = ________________ • 1 mole = 22.4 Liters • Example: During cellular respiration, a cell releases 2.1 mol of O2 gas. What volume is needed to hold that gas?

  15. Partner Practice • On a clean sheet of paper, show your work for 10-2 Practice Problems (1-3, 12-14, 17, 18, 23-25). Independent Practice (Homework) • Complete any assigned 10-2 Practice Problems above, and solve page 211 22 and 23.

  16. As you come in, • Put your homework on your desk. • Solve Example 6.7 on your notes - Juglone, a dye known for centuries, is produced from the husks of black walnuts. The formula for juglone is C10H6O3. • Calculate the molar mass of juglone. • A sample of 1.56 g of pure juglone was extracted from black walnut husks. How many moles of juglone does this sample represent? • How many atoms of carbon are present?

  17. Partner Evaluations • Spend 10 minutes with your partner comparing work - NOT JUST ANSWERS. • When you find differences, decide which version is BEST. • Mark questions to ask when we meet back as a large group.

  18. 10-2 Practice Problems • Any questions that you need me to solve.

  19. As you come in, • Put your Think Tac Toe on your desk. • We’ll take your quiz after a quick TTT check and review time. • New content begins at 2:40 pm. • HOMEWORK: 7-2 Section Review 1-3, % Composition WS 1-3, and Empirical & Molecular Formula Practice 1-3

  20. Thinking Critically About Moles • Knowledge Level Station • Show your knowledge of the mole concept by labeling the Mole Map graphic organizer. • Use the colored pencils to color-code your organizer. • RED = COUNTING PARTICLES • BLUE = WEIGHING SUBSTANCES • GREEN = AMOUNT OF SPACE TAKEN BY A GAS

  21. Thinking Critically About Moles • Comprehension Level Station • Explain the use of the mole map to your partner. Use the following calculation prompts in your explanation. Begin your explanation with “I would use my mole map to solve this calculation by...” • Partner One: How many grams of sucrose, C12H22O11 contain 0.79 moles? • Partner Two: The number of particles in 0.91 moles of ammonia is _____.

  22. Thinking Critically About Moles • Application Level Station • Use the conversion factors illustrated and explained on the Mole Map to compute solutions to the following. Show all of your work. • Calculate the number of grams of cobalt that contain the same number of atoms as 2.24 g of iron. • Apply the concept of the mole in order to determine which of the following statements is the most accurate description of a mole. • The number of atoms in 55.85 grams of iron. • The mass of carbon in a measured sample of carbon. • The number of atoms in any given mass of a molecule. • 6.022 x1023 grams of a sample of any element.

  23. Thinking Critically About Moles • Analysis Level Station • Use the substances and instruments at the station. Which substance will create a taller column in the graduated cylinder: 0.215 mol C12H22O11 or 0.972 mol NaHCO3? Measure and record the height of each in mL. • Compare the molar masses of the two substances. • If 7 balloons were filled with the 1 mole of each of the 7 diatomic gases, which balloon would weigh the most? The least?

  24. Thinking Critically About Moles • Synthesis/Evaluation Level Station • Check your homework from last night. Use a colored pencil to correct your mistakes. • Leave your corrected homework in the labeled folder.

  25. Starter • Polyvinyl chloride, called PVC, which is widely used for floor coverings (“vinyl”), is made form a molecule with the formula C2H3Cl. Calculate the MOLAR MASS of this substance. • Calcium carbonate, CaCO3 (also called calcite), is the principal mineral found in limestone, marble, chalk, pearls, and the shells of marine animals. • A certain sample of calcium carbonate contains 4.86 mol. What is the mass in grams of this sample? How many oxygen atoms are in 10g sulfur dioxide?

  26. Percent Composition • The relative amounts of each element in a compound are expressed in percent composition. AKA: percent by mass of each element • % of element = grams of element X 100 grams of compound

  27. % Composition Example • Carvone is a substance that occurs in two forms, both of which have the same molecular formula (C10H14O) and molar mass. One type of carvone give caraway seeds their characteristic smell; the other is responsible for the smell of spearmint oil. Compute the mass percent of each element in carvone.

  28. Connecting Moles & Mass % to Chemical Formulas • Mass % is easily related to chemical formulas • The relationship of moles to chemical formulas requires a little more thought...

  29. Type of Chemical Formula: Empirical Formula • Empirical formula: lowest whole number ratio of the atoms of the elements in a compound • Ionic compounds are criss-crossed and then reduced. Ionic compound formulas are nearly always empirical formulas. • Empirical formula doesn’t have to be the same as the actual molecular formula of the compound. • CH2O = empirical formula for GLUCOSE

  30. Empirical Formula • CH2O • Calculate the mass percent of each element. • C = 40% • H = 6.7% • O = 53.3% • Isn’t this the reduced formula for: C3H6O3, C4H8O4, C5H10O5, & C6H12O6 • The mass percent of each of these compounds is the same.

  31. Type of Chemical Formula: Molecular Formula • Molecular formula: actual formula for the compound which gives the composition of the molecule • Glucose shares an empirical formula with many compounds, but it has its molecular formula all to itself. • What is it’s molecular formula?

  32. Calculating Empirical Formula • Use a simple rhyme! • % to gram • Gram to mole • Divide by the smallest • Multiply ‘til whole.

  33. Calculating Empirical Formulas • When an unknown compound is found, instruments can tell scientists the mass percent composition of the compound. • Calculations are required to convert that series of percentages into a chemical formula. • We start by converting to the empirical formula.

  34. Empirical Formula Example 1: • An oxide of aluminum is formed by the reaction of 4.151 g of aluminum with 3.692 g of oxygen. Calculate the empirical formula for this compound. • % to gram = IS DONE FOR YOU • Gram to mole = dimensional analysis • Let’s carry out the calculation on the board.

  35. Formula Example 2 • A sample of lead arsenate, an insecticide used against the potato beetle, contains 1.3813 g of lead, 0.00672 g of hydrogen, 0.4995 g of arsenic, and 0.4267 g of oxygen. • Calculate the empirical formula for lead arsenate. (PbHAsO?)

  36. Calculating Molecular Formula • Molecular Formula= n(empirical formula) CH2O = glucose • We know how to calculate the empirical formula, but how do we know what number to multiply it by? n= molecular formula mass/molar mass of empirical

  37. Formula Example 3 • Glucose is analyzed and found to have an empirical formula of CH2O. The compound has a molar mass of 180.149 g/mol. What is the compound’s molecular formula?

  38. Formula Example 4 • The most common form of nylon is 63.68% carbon, 12.38% nitrogen, 9.80% hydrogen, and 14.4% oxygen. Calculate the empirical formula for nylon. • If the molar mass of the compound is 226.306g, what is it’s molecular formula?

  39. Priorities: • The Mole Think Tac Toe • Critical Thinking Stations • Empirical Formula Worksheet • Mole Practice Packet - Chemical Quantities Section 7.2 1-9

  40. Starter • Which is the best description of a mole? • Mass of carbon in a measured sample of carbon • # of atoms in any given mass of carbon • Number of atoms in 12.01 grams of carbon • How many Hydrogen atoms are in 20g of H2O2? • Octane (C8H18), a compound of hydrogen and carbon, has a molar mass of 114.26g/mol. If one mole of the compound contains 18.17g hydrogen, what is it’s empirical formula?

  41. Challenging Molar Mass Problems • What mass of strontium contains the same number of atoms as 15g of beryllium metal? • Consider a 5g sample of sodium and a 10.1g sample of an unknown metal. There are exactly half as many atoms of the unknown as in the 5 grams of sodium. What is the unknown metal?

  42. Starter • What is the percent by mass of hydrogen in acetic acid? • A container contains 10g carbon dioxide at STP, what is the volume the gas? • The final product in protein metabolism is urea. Urea contains 20.00% C, 6.73% H, 46.65% N, and 26.64% O. The molar mass of urea is 60.07g/mol. Calculate the molecular formula.

  43. Challenging Molar Mass Problem • Calculate the number of grams of potassium that contain the same number of atoms as 6g of cesium. • Consider a 10g sample of gold and a 4g sample of an unknown element. There are exactly half as many atoms of the unknown as in the 10 gram of gold. What is the unknown element?

  44. Starter • Which weighs more, 1.5 mol of bromine or 15 mol of lithium metal? • A single molecule of a compound has a mass of 1.461 x 10-22g. Could it be NO or CF4 ? • What is the empirical formula for disulfur tetraoxide? • Find the molecular formula of a compound that consists of 56.36% oxygen and 43.64% phosphorus. The molar mass of the compound is 425.83g/mol.

  45. Challenging Molar Mass Problems • A single molecule of a compound has a mass of 7.0399 x 10-23g. Could it be LiCl or NaF? • Consider a 10g sample of nitrogen and a 13g sample of an unknown metal. There are exactly twice as many atoms of the unknown as in the 10 grams of nitrogen. What is the unknown metal?

  46. Bonus (2 pts each) • A tube contains 25g helium at STP, what is the volume the gas? • If a sample contained 10g of Li, how many lithium oxide formula units would you have? • Consider a 20g sample of gold and a 4g sample of an unknown element. There are exactly half as many atoms of the unknown as in the 20 gram of gold. What is the unknown element?

  47. Empirical / Molecular Formula • A compound used as an additive for gasoline to help percent engine knock shows the following percentage composition: • 71.65% Cl • 24.27% C • 4.07% H The molar mass is known to be 98.96 g. Determine the empirical formula and the molecular formula for this compound.

  48. Empirical / Molecular Formula • A compound used as an additive for gasoline to help percent engine knock shows the following percentage composition: • 71.65% Cl • 24.27% C • 4.07% H The molar mass is known to be 98.96 g. Determine the empirical formula and the molecular formula for this compound.

  49. STARTER • TAKE 5: • Minutes to look over your notes and important formulas • Minutes to ask any last questions before your test

  50. As you come in, • Complete Review Stations 1-24. Write down the station number, your work, and circle your answer. • When you have completed the stations, return to your seat. You should turn in any Mole Day proposals and/or complete the extra credit with additional time. • We’ll meet together at 2:35 pm to check station answers and watch a video.

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