CHEM 1211 Lecture 7 Outline of Last Lecture I Moles II Formula Weight III Calcium Carbonate IV Percent Composition V Elemental Composition Outline of Current Lecture I Balancing Chemical Equations A Law of Conservation of Matter II Classification of Solutes A Aqueous Solutions B Two Classes of Solutes 1 Electrolytes 2 Non Electrolytes III Chemical Reactions Current Lecture I Balancing Chemical Equations 1 CH4 2O2 CO2 2H2O 2 Fe2O3 3CO 2Fe 3CO2 adding heat 1 formula unit 3 molecules 2 atoms and 3 molecules NA formula units 3 molecules 2NA atoms and 3NA molecules 1 mol Fe2O3 3 mols CO 2 mols Fe and 3 mols CO2 Molar masses 159 70 g mol 28 00 g mol 55 85 g mol 44 00 g mol A Law of Conservation of Matter Coefficients must be the least whole number ratio 3 2 1 C4H10 g 13 2 O2 g 4CO2 g 5H2O g 8O 5O Atoms Atoms 2 C4H10 g 13 O2 g 8CO2 g 10 H2O g C4H10 Butane 4 NH3 Ammonia 2NH3 g 5 2 O2 g 2NO g 3H2O g 4NH3 g 5O2 g 4NO g 6H2O g 5 C2H6O ethanol 1C2H6O l 3O2 g 2CO2 g 3H2O g Has 9 Coefficients II Classification of Solutes A Aqueous Solutions 1 Mix solute solvent 2 Solvent water 3 Solute a Dissolution Process C6H12O6 s C6H12O6 aq Covalent molecular compounds b MX s M aq X aq ionic compound 8 5 13 O atoms B Two Classes of Solutes 1 Electrolytes Dissociate ionize in solution Example SrBr2 s Sr2 aq 2 Br aq a Strong HCl Dissociate 100 Conduct electricity even in dilute solutions Strong soluble molecular acids HCl HNO3 Strong soluble molecular bases NaOH KOH Soluble ionic salts NaCl Ionize in H2O 100 b Weak HF Dissociate 100 more like 10 etc Do not really conduct electricity well Weak acids CH3COOH acetic acid Weak bases NH3 Fe OH 3 Soluble covalent salts which ionize in H2O 100 2 Non Electrolytes Do not conduct electricity well Opposite of Electrolytes Chemical sources Molecular compounds dissolved in H2O Examples C2H5OH Ehtanol or C6H12O6 Glucose III Chemical Reactions Examples 1 Pb NO3 2 aq 2NaI aq PbI2 s 2NaNO3 aq This is an exchange precipitation and metathesis reaction
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