What is a Mole? Questions Answers

Assignment 5.1 – What is a Mole? - - - The mole is a counting unit (similar to a dozen) o Except instead of 12, it’s 602 billion trillion 602,000,000,000,000,000,000,000 o It is commonly written as: 6.02 X 1023 (in scientific notation) The mole works just like other counting units 1 mole of cookies = 6.02 X 1023 cookies o 1 dozen cookies = 12 cookies o 1 dozen cars = 12 cars o 1 pair of shoes = 2 shoes 1 mole of cars = 6.02 X 1023 cars 1 mole of shoes = 6.02 X 10 23 cars This number is named in honor of Amedeo AVOGADRO (born 1776 – died 1856), who studied quantities of gases and discovered that no matter what the gas was, there were the same number of molecules present o So 6.02 x 1023 is known as Avogadro’s Number Learning Check – please circle the correct answer 1. How many sulfur atoms are in a mole of sulfur atoms? a. 12 atoms b. 602 atoms c. 6.02 x 1023 atoms d. 6.02 x 1012 atoms 2. Suppose we invented a new collection unit called a rapp. One rapp contains 8 objects. How many oranges are in 2.0 rapps? a. 8 oranges b. 12 oranges c. 16 oranges d. 6.02 x 1023 oranges The coolest thing about the mole: you can find the mass of 1 mole of an atom by looking up its atomic mass from the periodic table! The mass of a mole of any compound is equivalent to the sum of the atomic masses of the elements that make up that compound! This means: 1 1 mole of atoms is 6.02 x 1023 atoms and has a mass of that atom’s atomic mass! Assignment 5.2: Calculating Molar Mass How to calculate Molar mass: 1. Look at the chemical formula of the compound 2. Find the Atomic Mass for each element (there is a periodic table on the last page of this packet!) 3. Add the totals together 4. Round to the nearest 0.01 place Example 1: Example 2: Find the Molar Mass of SO3 Find the Molar Mass of Ba(NO3)2 1 S atom x 32.066 = 32.066 g/mol 3 O atoms x 15.999 = 47.997 g/mol 32.066 g/mol + 47.997 g/mol =80. 063 g/mol The molar mass of SO3 is 80.06 g/mol 1 Ba atom x 137.327= 137.327 g/mol 2 N atoms x 14.007 = 28.014 g/mol 6 O atoms x 15.999=95.994 g/mol 137.327 g/mol + 28.014 g/mol + 95.994 g/mol = 261.335 g/mol The molar mass of Ba(NO3)2 is 261.34 g/mol Calculate the molar mass and mass of 1 mole of each compound. Show you work and don’t forget units. Molar mass is in grams/mole. Mass is in grams. 1. N2 Molar mass of N2 ____________. 1 mole of N2 has a mass of ____________. 2. H2O Molar mass of H2O ____________. 1 mole of H2O has a mass of ____________. 3. CuCl2 4. C6H12O6 Molar mass of C6H12O6 ____________. 1 mole of C6H12O6 has a mass of ____________. 5. CaCO3 Molar mass of CaCO3 ____________. 1 mole of CaCO3 has a mass of ____________. 6. (NH4)2O Molar mass of (NH4)2O is ____________ 1 mole of (NH4)2O has a mass of ____________. Molar mass of CuCl2 ____________. 1 mole of CuCl2 has a mass of ____________. 2 Assignment 5.3: Moles and Mass Wrap Up If you need additional space, show work on a separate page and turn in your work with your packet. Part 1: Reviewing the mole 1. If I have “one mole” of atoms, how many atoms do I have? 2. If I have 3 moles of donuts, how many donuts do I have? 3. If I have ½ a mole of carbon, how many carbon atoms do I have? Part 2: Molar Mass Calculate the molar mass of each of the following. You must show all of your work to get credit for these problems. “I just did it in my calculator” is not an acceptable response. A periodic table is included as the last page of this packet!!! 4. KF 5. H2S 6. NaNO3 7. Mg(OH)2 8. Al2(SO4)3 Part 3: Using Molar Mass Use the molar masses you calculated in part 2 above to answer the following questions. The table below shows an example problem. You must show all of your work to get credit for these problems. “I just did it in my calculator” is not an acceptable response. Example: If I have 1 mole of KF, how much will it weigh? How many molecules will it be? What about 2 moles? Moles KF 1 mole KF 2 moles KF Mass/Weight 58.096 grams 2 x 58.096 = 116.192 grams Molecules 6.02 x 1023 molecules 2 x (6.02 x 1023) = 12.04 x 1023 molecules 9. How much will 1 mole of H2S weigh? 10. How much will 0.50 moles of NaNO3 weigh? 11. How much will 3 moles of Mg(OH)2 weigh? 12. If I have about 68.2 grams of H2S, how many moles do I have? 13. If I have about 342.15 grams of Al2(SO4)3, how many molecules do I have? 3 Answer Keys 5.1 1) 6.02 x 10 23 atoms 2) 16 oranges 5.2 1. N2 Molar mass of N2 ______28.01 g/mol______. 1 mole of N2 has a mass of _____28.01g_______. 2. H2O Molar mass of H2O _______18.02g/mol_____. 1 mole of H2O has a mass of _____18.02g _______. 3. CuCl2 Molar mass of CuCl2 ____134.45g/mol________. 1 mole of CuCl2 has a mass of ____134.45g________. 4. C6H12O6 Molar mass of C6H12O6 _____180.16g/mol_______. 1 mole of C6H12O6 has a mass of _____180.16g_______. 5. CaCO3 Molar mass of CaCO3 ___100.09g/mol_________. 1 mole of CaCO3 has a mass of ___100.09g_________. 6. (NH4)2O Molar mass of (NH4)2O is __52.08g/mol__________ 1 mole of (NH4)2O has a mass of ____52.08g________. 5.3 Part 1 1. If I have “one mole” of atoms, how many atoms do I have? 6.02 x 10 23 atoms 2. If I have 3 moles of donuts, how many donuts do I have? 3 x 6.02 x 10 23 atoms = 1.81 x 1024donuts 3. If I have ½ a mole of carbon, how many carbon atoms do I have? 6.02 x 10 23 atoms / 2 = 3.01 x 1023 carbon atoms Part 2 4. KF = 58.10 g/mol 5. H2S =34.10 g/mol 6. NaNO3 = 84.99 g/mol 7. Mg(OH)2 = 58.32 g/mol 8. Al2(SO4)3 =342.15g/mol Part 3 9. How much will 1 mole of H2S weigh? 34.10 g 10. How much will 0.50 moles of NaNO3 weigh? 42.50 g 11. How much will 3 moles of Mg(OH)2 weigh? 174.96 g 12. If I have about 68.2 grams of H2S, how many moles do I have? 2 moles (2.00 mols with sigfigs!) 13. If I have about 342.15 grams of Al2(SO4)3, how many molecules do I have? 6.02 x 1023 molecule 4 14. 1 1 Periodic Table of Elements 2 H He Hydrogen 2 1.008 3 18 Li Lithium 6.941 11 Na Sodium 22.99 19 K Potassium 39.10 37 Rb Rubidium 85.47 55 Cs Cesium 132.9 87 Fr Francium (223) 4 13 6 Be Key: Beryllium 9.012 Atomic Number C 5 Symbol Name 12.01 Average Atomic Mass B Boron Carbon 10.81 12 13 Magnesium Aluminum Mg 24.31 20 Ca Calcium 40.08 38 Sr Strontium 87.62 56 Ba Barium 137.3 88 Ra Radium 226 Al 3 21 Sc Scandium 44.96 39 Y Yttrium 88.91 57 La Lanthanum 138.9 89 Ac Actinium (227) 4 22 Ti Titanium 47.88 40 Zr Zirconium 91.22 72 Hf Hafnium 178.5 104 Rf Rutherfordium (261) 5 6 7 8 23 24 25 Vanadium Chromium Manganese 41 42 43 Molybdenum Technetium Ruthenium V 50.94 Nb Niobium 92.91 73 Ta Tantalum 180.9 105 Db Dubnium (262) Cr 52.00 Mo 95.94 74 W Tungsten 183.9 106 Sg Seaborgium (266) Mn 54.94 Tc (98) 75 Re Rhenium 186.2 107 Bh Bohrium (264) 26 Fe Iron 55.85 44 Ru 101.1 76 Os Osmium 190.2 108 Hs Hassium (277) 9 27 Co Cobalt 58.93 45 Rh Rhodium 102.9 77 Ir Iridium 192.2 109 Mt 10 28 Ni Nickel 58.69 46 Pd Palladium 106.4 78 Pt Platinum 195.1 110 Ds 11 29 Cu Copper 63.55 47 Ag Silver 107.9 79 Au Gold 197.0 111 Rg 12 30 Zn Zinc 65.41 48 Cd Cadmium 112.4 80 Hg Mercury 200.6 112 (269) (272) 31 Ga Gallium 69.72 49 In Indium 114.8 81 Tl Thallium 204.4 113 6 C Carbon 12.01 14 Si Silicon 28.09 32 Ge Germanium 72.59 50 Sn Tin 118.7 82 Pb Lead 207.2 114 15 7 N Nitrogen 14.01 15 P Phosphorus 30.97 33 As Arsenic 74.92 51 Sb Antimony 121.8 83 Bi Bismuth 209.0 115 16 8 O Oxygen 16.00 16 S Sulfur 32.07 34 Se Selenium 78.96 52 Te Tellurium 127.6 84 Po Polonium (209) 17 9 F Fluorine 4.003 10 Ne Neon 19.00 20.18 17 Cl Chlorine 18 Ar Argon 35.45 39.95 35 Br Bromine 36 Kr Krypton 79.90 83.80 53 I Iodine 54 Xe Xenon 126.9 131.3 85 At Astatine (210) 86 Rn Radon (222) 112 Uub Uut Uuq Uup Uub Meitnerium Darmstadtiu Roentgeniu Ununbium m m (268) 26.98 14 Helium (277) Ununtrium Ununquadiu Ununpentiu m m (284) (289) (288) Ununhexiu m 5