CHEM 1211 Lecture 7Outline of Last Lecture I. MolesII. Formula WeightIII. Calcium CarbonateIV. Percent CompositionV. Elemental CompositionOutline of Current Lecture I. Balancing Chemical EquationsA. Law of Conservation of MatterII. Classification of SolutesA. Aqueous SolutionsB. Two Classes of Solutes1. Electrolytes2. Non-ElectrolytesIII. Chemical ReactionsCurrent LectureI. Balancing Chemical Equations1. CH4 + 2O2 CO2 + 2H2O2. Fe2O3 + 3CO 2Fe + 3CO2*** = adding heat1 formula unit 3 molecules 2 atoms and 3 moleculesNA formula units 3 molecules 2NA atoms and 3NA molecules1 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/molA. Law of Conservation of Matter- **Coefficients must be the least whole number ratio3. 2(1 C4H10(g) + (13/2)O2(g) 4CO2(g) + 5H2O(g)) 8 O 5 O 8+5 = 13 O atoms Atoms Atoms2 C4H10(g) + 13 O2(g) 8CO2(g) + 10 H2O(g)C4H10= Butane4. NH3 = Ammonia2NH3(g) + (5/2)O2(g) 2NO(g) 3H2O(g)4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g)5. C2H6O= ethanol1C2H6O(l) + 3O2(g) 2CO2(g) + 3H2O(g)**Has 9 Coefficients! II. Classification of SolutesA. Aqueous Solutions1. Mix solute + solvent2. Solvent = water3. Solute = ?a. Dissolution Process- C6H12O6(s) C6H12O6(aq)- Covalent/molecular compoundsb. MX(s) M+ (aq) + X-(aq) : ionic compoundB. Two Classes of Solutes1. 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 - GlucoseIII. Chemical ReactionsExamples: 1. Pb(NO3)2(aq) + 2NaI(aq) PbI2(s) + 2NaNO3(aq)This is an exchange, precipitation, and metathesis
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