Chemistry 121 Oregon State UniversityWorksheet 5 Notes Dr. Richard L NafshunA. A student obtains 4.000 moles of carbon atoms. How many carbon atoms are present? What is the mass of this sample?4.000 moles C atoms mole1atoms10x022.623 = 2.408 x 1024 C atoms4.000 moles C atoms mole1g011.12 = 48.04 g carbon1. Determine the molar masses (AKA atomic masses) of C, N, O, F, Ne, and U.C = 12.01 g/mol.N = 14.01 g/mol.O = 16.00 g/mol.F = 19.00 g/mol.Ne = 20.18 g/mol.U = 238.03 g/mol.2. Determine the molar masses of methane, the O2 molecule, carbon dioxide, and water.Methane (CH4):1 x 12.01 g/mol+ 4 x 1.01 g/mol_________________16.05 g/molO2:2 x 16.00 g/mol = 32.00 g/molCO2:1 x 12.01 g/mol+ 2 x 16.00 g/mol_________________44.01 g/molH2O:2 x 1.01 g/mol+ 1 x 16.00 g/mol_________________18.02 g/mol3. Determine the molar mass of elemental aluminum ("just plain aluminum metal"), HCl, aluminum chloride, and the H2 molecule.Al is 26.98 g/mol.HCl is 36.46 g/mol.AlCl3 is 133.33 g/mol.H2 is 2.02 g/mol.4. Determine the molar mass of calcium sulfate [CaSO4].136.15 g/mol.5. Determine the molar mass of aluminum nitrate [Al(NO3)3].213.01 g/mol (each of the three nitrate ions is 62.01 g/mol)6. Determine the molar mass of aluminum sulfide—what is the correct chemical formula?Al2S3 is 150.17 g/mol.7. Determine the molar mass of sodium sulfate [Na2SO4].142.07 g/mol.8. Determine the molar mass of calcium acetate.Ca(CH3COO)2 is 158.18 g/mol.9. A student obtains 1.8066 x 1024 carbon dioxide molecules. Calculate the mass of this sample.1.8066 x 1024 CO2 molecules moleculesxmol2310022.61molg101.44132.1 g CO210. A student obtains 64.00 grams of oxygen gas (O2). How many moles of O2 are present? How many oxygen molecules are present?64.00 g O2 molgmolO/00.3212= 2.000 moles O22.000 moles O2 molmoleculesx110022.6231.204 x 1024 O2 molecules11. A student obtains 50.00 grams of nitrogen gas (N2). How many moles of N2 are present? How many nitrogen molecules are present?50.00 g N2 molgmolN/02.2812= 1.784 moles N21.784 moles N2 molmoleculesx110022.6231.075 x 1024 N2 molecules12. A student obtains 12.00 grams of hydrogen gas (H2). How many moles of H2 are present? How many hydrogen molecules are present? How many hydrogen atoms are present? How many protons are present? How many electrons are present?12.00 g H2 molgmolH/02.212= 5.941 moles H25.941 moles H2 molmoleculesx110022.6233.577 x 1024 H2 molecules3.577 x 1024 H2 molecules moleculeHHatoms2127.155 x 1024 H atoms7.155 x 1024 H atoms Hatomproton11= 7.155 x 1024 protons7.155 x 1024 H atoms Hatomelectron11= 7.155 x 1024 electrons13. A student obtains 100.00 grams of sulfur hexafluoride gas (SF6). How many moles of SF6 are present? How many SF6 molecules are present? How many sulfur atoms are present? How many fluorine atoms are present? How many electrons are present?100.00 g SF6 molgmol/07.146SF16= 0.6846 moles SF60.6846 moles SF6 molmoleculesx110022.6234.123 x 1023 SF6 molecules4.123 x 1023 SF6 molecules moleculeSFSatom6114.123 x 1023 S atoms4.123 x 1023 SF6 molecules moleculeSFFatoms6162.474 x 1024 F atoms4.123 x 1023 SF6 molecules moleculeSFelectrons61702.886 x 1025 electrons14. A student obtains 50.00 grams of calcium hydroxide. Determine the number of hydroxide ions present in the sample. Determine the numbers of calcium ions present.50.00 grams Ca(OH)2 gmol02.741 = 0.6755 moles Ca(OH)20. 6755 moles Ca(OH)2 molunitsx110022.6234.068 x 1023 Ca(OH)2 units (The term units is used here rather than molecule because Ca(OH)2 is an ionic compound, not a molecule).4.068 x 1023 Ca(OH)2 units unitOHCaionCa22)(114.068 x 1023 Ca2+ ions4.068 x 1023 Ca(OH)2 units unitOHCaionsOH2)(128.136 x 1023 OH-