CHEM 1211L Lab Begins Next Week Dress Code Safety Goggles or Glasses must be worn at all times Z87 or Z87 1 No food or drink is permitted in the lab room You must complete the Safety Quiz and Prelab Questions for Exp 1 Withdrawal Policy Students who choose to withdraw from lecture CHEM 1211 before Monday October 17th must withdraw from the lab CHEM 1211L Students who choose to withdraw from lecture between Monday October 17th and the Withdrawal Deadline Thursday October 20th may choose to remain in the lab IF they are passing the lab Withdrawal Policy Students that withdraw from CHEM 1211 prior to 5 00 PM on Thursday October 20th will receive WP s regardless of their present grade in CHEM 1211 Ch 2 end of book HW questions 12 13 15 18 22 23 28 32 34 36 38 40 42 44 45 49 50 53 54 56 60 62 66 68 70 72 76 78 80 82 86 87 89 91 93 96 105 106 114 Buy individual lab experiments cengagebrain com Need same lab manual for 1212 Review of nomenclature Copper II bromide CuBr2 Potassium nitrate K NO3 Ammonium sulfate NH4 2SO4 Copper I sulfide Cu2S MgO Magnesium Oxide CO2 Carbon Dioxide AgCl Silver Chloride CH3CH2CH3 Propane NH3 Ammonia Benzene C6H6 Atomic weights atomic mass Atomic mass unit amu defined as exactly 1 12 of the mass of an atom of a particular kind of carbon atom called carbon 12 Periodic table has amu The Mole Defined as the amount of substance that contains as many entities formula units ions atoms molecules or other particles as there are atoms in exactly 0 012 kg of pure carbon 12 atoms 1 mole 6 022 x 1023 particles formula units Avogadro s number Mole derived from the Latin word moles which means a mass molecule is the diminutive form of this word and means a small mass 1 mole of X atoms atomic mass of X element 2 moles of O2 is how many grams 1 mole of H2 2 00 g mol H2 1 mole of O2 32 00 g mol 02 2 mole O2 x 32 00 g mol 64 00 g of O2 1 mole of He 4 00 g 6 022 x 1023 atoms of He 1 mole of H2 6 022 x 10 23 molecules of H2 2 6 022 x 1023 atoms of H2 1 20 x 1024 H atoms Q1 1 23 moles of Ca is how many g 1 23 moles of Ca 1 23 40 08 49 3 g mol of Ca How many atoms are contained in 1 245 moles of Na 1 245 moles 6 022 x 1023 7 497 x 10 23 Formula weights molecular weights and moles The formula weight of a substance is the sum of the atomic weights of the elements in the formula each taken the number of times the element occurs Formula weight used for either ionic or molecular substances Molecular weight used for non ionic substances Write the formula for ammonium hydroxide NH4OH What is its formula weight 1 x N 14 0g mol 5 x H 5 00 g mol 1 x 0 16 00 g mol 35 0 g mol How many g are in 2 5 moles How many N atoms are there 35 0 g mol 2 5 moles 88 g 2 5 moles NH4OH 6 022 x 10 23 formula unit mole 1 N 1 formula unit 1 5 x 1024 atoms of N Write the formula for aluminum sulfate Al2 SO4 3 What is its formula weight 2 x Al 53 96 g mol of Al 3 x S 96 21 g mol of S 12 x O 192 00 g mol of O 342 17 g mol of Al2 SO4 3 How many g are in 1 2 moles How many atoms of Al are there O atoms 1 2 mol 342 17 g mol of Al2 SO4 3 4 1 x 102 g 1 2 moles Al2 SO4 3 6 022 x 10 23 formula unit mole 2 Al 1 formula unit 1 4 x 1024 atoms of Al 1 2 moles Al2 SO4 3 6 022 x 10 23 formula unit mole 12 O 1 formula unit 8 7 x 1024 atoms of o Q2 Write the formula for Fe III phosphate What is its formula weight Enter that into clicker How many moles are in 50 0 g of sodium hydroxide Percent composition and formulas of compounds Percent composition of water Derivation of formulas from elemental composition Empirical simplest formula is the smallest whole number ratio of atoms present Example benzene molecular formula C6H6 so empirical formula is Molecular formula indicates the actual numbers of atoms present in a molecule of the compound Calculate the composition of potassium sulfate So 44 9 of K and 18 4 of S and 36 7 of O adds up to 100 then assume you have 100 g of the compound calculate the number of moles of each element in the formula so becomes g then divide the moles by the lowest number in moles should get whole numbers and that s how you calculate the empirical formula The analysis of a salt shows that it contains 56 58 potassium 8 68 carbon and 34 78 oxygen Calculate the empirical formula for this substance 63 6 N 36 4 O calculate the empirical formula