110_Fa11_LUZ-week12ST (1)

110_Fa11_LUZ-week12ST (1) - Week 12: Lectures 34 36 Lecture...

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Week 12: Lectures 34 – 36 Lecture 34: W 11/9 Lecture 35: F 11/11 Lecture 36: M 11/14 Reading: BLB Ch 3.1 – 3.2; 3.6 – 3.7; 4.2 – 4.4 Homework: BLB 3: 1, 64; 4: 24, 39; Supp Rxns: 1 – 11 Reminder: No Angel Quiz on Thur 11/10 ALEKS Objective 12 due on Tues 11/15 Jensen Office Hour: 501 Chemistry Building Tuesdays and Thursdays 10:30 – 11:30 am Late drop deadline: Friday 11/11 @11:59 pm Final Exam: Monday Dec 12 2:30 – 4:20 pm 4,5’,)6 7&8( 98&( :+;,0 <= >-*( ?@A,#’0, Jensen Chem 110 Chap 3 & 4 Page: 2 Chemical Reactions Law of conservation of mass: total mass does not change during a chemical reaction • Mass of reactants MUST equal mass of products # of atoms of each element on reactant side = # of atoms of each element on product side Example: Complete combustion of pentane C 5 H 12 + 8 O 2 ! 5 CO 2 + 6 H 2 O If mass of reactants is 100 g, then the mass of products must be ______ g. Reactants: ____C, ____H, ____O atoms Products: ____C, ____H, ____O atoms ___ mol C 5 H 12 react completely with ____ mol O 2 , produce ____ mol CO 2 and ____ mol H 2 O .
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Jensen Chem 110 Chap 3 & 4 Page: 3 Balancing Chemical Equations When reactants and products are both given, chemical reactions are balanced by changing the _____________. Four “Easy” Rules 1. Write the unbalanced molecular equation correctly (molecules involved with correct molecular formulas) C 6 H 6 + O 2 ! CO 2 + H 2 O 2. Balance the atoms of one element. C 6 H 6 + O 2 ! CO 2 + H 2 O 3. Balance atoms of remaining elements C 6 H 6 + O 2 ! CO 2 + H 2 O 4. Check you work! Make sure that you use the smallest whole numbers . Jensen Chem 110 Chap 3 & 4 Page: 4 Example: When the following equation C 4 H 8 O 2 (l) + O 2 (g) ! CO 2 (g) + H 2 O(g) is balanced with the smallest possible set of integer coefficients, the coefficient of O 2 is A. 1 B. 2 C. 3 D. 5 E. 6 How many moles of water will be produced if 3 moles of C 4 H 8 O 2 burn completely in air?
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Jensen Chem 110 Chap 3 & 4 Page: 5 Patterns of Reactivity 1. Combination reactions (Chapter 3) Elements react to form compounds 2 Mg (s) + O 2 (g) ! 2 MgO (s) Small compounds combine to form larger ones MgO (s) + CO 2 (g) ! MgCO 3 (s) 2. Decomposition reactions (Chapter 3) 2 H 2 O (l) ! 2 H 2 (g) + O 2 (g) CaCO 3 (s) ! CaO (s) + CO 2 (g) 3. Complete Combustion reactions (Chapter 3) CH 4 (g) + 2 O 2 (g) ! CO 2 (g) + 2 H 2 O(g) All hydrocarbons will produce ___________ when they undergo complete combustion reactions. 4. Single displacement reactions (Chapter 4) Zn(s) + CuSO 4 (aq) ! ZnSO 4 (aq) + Cu(s) Jensen Chem 110 Chap 3 & 4 Page: 6 Patterns of Reactivity 5. Exchange reactions (Chapter 4) (Double Displacement or Metathesis Rxn) Exchange reactions only occur if there is a driving force a. Precipitation Pb(NO 3 ) 2 (aq) + 2 KI(aq) ! PbI 2 (s) " + 2 KNO 3 (aq) b. Neutralization (weak or non-electrolyte) NaOH(aq) + HCl(aq) ! NaCl(aq) + H 2 O( ! ) c. Gas formation 2 HCl(aq) + Na 2 S(aq)
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110_Fa11_LUZ-week12ST (1) - Week 12: Lectures 34 36 Lecture...

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