FTCE Chemistry SAE Preparation Course Session 2 Lisa Baig Instructor Session Norms • Respect – No side bars – Work on assigned materials only – Keep phones on vibrate – If a call must be taken, please leave the room to do so Course Outline Session 1 Review Pre Test Competencies 6, 7 and 8 Competencies 1 & 2 Competency 5 Session 2 Competency 3 Competency 4 Post Test Required Materials • Scientific Calculator • 5 Steps to a 5: AP Chemistry – Langley, Richard, & Moore, John. (2010). 5 steps to a 5: AP chemistry, 2010-2011 edition. New York, NY: McGraw Hill Professional. • Paper for notes • State Study Guide Chemistry Competencies 1. Knowledge of the nature of matter (11%) 2. Knowledge of energy and its interaction with matter (14%) 3. Knowledge of bonding and molecular structure (20%) 4. Knowledge of chemical reactions and stoichiometry (24%) 5. Knowledge of atomic theory and structure (9%) 6. Knowledge of the nature of science (13%) 7. Knowledge of measurement (5%) 8. Knowledge of appropriate laboratory use and procedure (4%) Electronegativity • Fluorine is the most electronegative element. • Pattern of increasing electronegativity moves from bottom to top, and from left to right across the periodic table. Chemical Bond Mutual electrical attraction between the nuclei and valence electrons of different atoms that bind the atoms together Atoms would like to have 8 Valence electrons. These bonds help the atoms to achieve their full valence shells Three Types Ionic Covalent Metallic Ionic Bond • Force of attraction between oppositely charged ions • Occurs between Metal and Non-Metal elements • The Non-metal “steals” the valence electron(s) from the Metal • Forms a crystalline structure of these positive and negative charges • Typically solids at room temperature Ionic Character • Ionic Bonds are bonds with > 50% ionic character • Difference in Electronegativity of involved atoms is >1.7 Covalent Bond • Sharing of valence electron pairs by 2 atoms • Occurs between 2 Non-metal elements – Or the SAME non-metal element • Can share one, two or three pairs of electrons – Single Bond = 1 pair (1 sigma) – Double Bond = 2 pairs (1 sigma, 1 pi) – Triple Bond = 3 pairs (1 sigma, 2 pi) • Sharing can also be “unequal” – Called a POLAR covalent bond • Typically liquids or gases at room temperature Character • Ionic Character: – Polar Covalent Bonds have between 5% and 50% ionic Character – Non-Polar Covalent Bonds have less than 5% ionic character • Difference in Electronegativities – Polar Covalent Bonds have between 0.3 and 1.7 as a difference in electronegativities – Non-Polar Covalent bonds have less than 0.3 difference in electronegativities Break Time Take a 10 minute break Ionic Compounds • Ion names are used in combination • Cation- same as the element – Transitional Metals use Roman Numerals to represent Charge • Anion- replace the ending syllable of the element name with –ide • Polyatomic Ions- use the name of that iondo not try to rename. Use “criss-cross” to determine charges CuCl2 Copper (II) Chloride CuO Copper (II) Oxide NaCl Sodium Chloride KI Potassium Iodide Mg3N2 Magnesium Nitride PbO2 Lead (IV) Oxide Lewis Structures • A way to show the octet rule in molecules Practice • Draw the lewis structures for – Ammonia (NH3) – Water (H2O) – Phosphorus Trifluoride (PF3) – Hydrogen Cyanide (HCN) – Ozone (O3) – Formaldehyde (CH2O) VSEPR •AB5 •Trigonal bipyramidal •AB6 •Octahedral VSEPR • AB4 – Tetrahedral – 109.50 Bond Angles • AB3 – Trigonal Planar – 1200 Bond Angles • AB2 – Linear – 1800 Bond Angles VSEPR • AB2E – Bent or Angular • AB2E2 – Bent or Angular • AB3E – Trigonal Pyramidal Polarity? • The potential for opposite charges at different areas of a molecule Shape and Polarity? • What is the shape and polarity of the following molecules? – Water – Ammonia – Carbon Tetrachloride – Carbon Dioxide – Hydrogen Chloride Hybrids • Atoms “don’t like” to have empty orbitals • Hybridization – Mixing of 2 or more atomic orbitals of similar energies to produce new hybrid orbitals of equal energies • It works like this – Methane: CH4 Normally: 1s22s22p2 – Through hybridization- it forms an “sp” orbital, with 4 electrons total – New arrangement: 1s22(sp3) 4 Hybrid Orbitals Atomic Orbitals Type of Hybrid Number Molecular of Orbitals Geometry s p sp 2 s p p sp2 3 s p p p sp3 4 1800 Linear 1200 Trigonal Planar 109.50 Tetrahedral What type of hybrid? • Beryllium fluoride – BeF2 – sp • Ammonia – NH3 – sp2 • Methane – CH4 – sp3 Break Time Take a 10 minute break Spectroscopy • Devices that measure the interaction between matter and energy • Absorption – Measures the wavelengths of electromagnetic waves absorbed by a substance • X-Ray spectroscopy – Used to determine elemental composition and types of bonding Spectroscopy • UV – Used to quantify DNA and Protein concentration • Infrared – Used to determine bond type • Bonds resonate when exposed to the radiation • Nuclear Magnetic Imaging (NMR) – Used to determine bond structure Simple Organics • Alkanes (end in –ane) – Containing only single bonds – CnH2n+2 • Alkenes (end in –ene) – Containing at least one double bond – CnH2n • Alkynes (end in –yne) – Containing at lease one triple bond – CnH2n-2 Simple Organics Name Number of Carbons Meth- 1 Eth- 2 Prop- 3 But- 4 Pent- 5 Hex- 6 Hept- 7 Oct- 8 Non- 9 Dec- 10 Functional Groups Compound Type Alcohol Suffix or Prefix Image -OH -ol Haloalkane -X Halo- Amine -CN- -amine Aldehyde -COH -al Ketone - -COC- -one Carboxylic Acid -COOH -oic acid Ester -COOC- -oate Naming and Formulas • Numbers are used in the name to designate locations of the following – Types of bonds – Branches – Attached functional groups • For Example – – – – – 2,2,4- trimethylpentane 1-pentyne 2,3,4- trimethylnonane 2-methyl 3-hexene 2- propanol Macromolecules • Carbohydrates – Chains of carbon, hydrogen and oxygen. – Isomers • Lipids – Fatty acids- Chains of Carbon and Hydrogen • Proteins – Chains of Amino acids – Differ in their R group • Nucleic Acids – Chains of Nucleic Acids Organic Compound Naming • Numbers are used in the name to designate locations of the following – Types of bonds – Branches – Attached functional groups • For Example – – – – – 2,2,4- trimethylpentane 1-pentyne 2,3,4- trimethylnonane 2-methyl 3-hexene 2- propanol Lunch Time We start Again In ONE HOUR Determining Empirical Formulas • Say you have 65.0g of compound containing Na and Cl. • Determine the Empirical Formula if the compound is 39.3% Na and 60.7%Cl Higher Level Practice • 1st Step: Convert your percentages to mass of each element present • Na: (.393)(65.0g)= 25.545g Na • Cl: (.607)(65.0g) = 39.455g Cl Higher Level Practice • 2nd Step: Determine number of moles of each element in the sample 25.545g Na 1 mole = 1.11 mol Na 22.989 g/mol 39.455g Cl 1 mole = 1.11 mol Cl 35.453 g/mol Higher Level Practice • 3rd Step: Use these moles to determine the smallest whole number ratio of elements to each other. That is your empirical formula! 1.11 mol Na : 1.11 mol Cl 1 mol Na : 1 mol Cl Empirical Formula = NaCl Balancing Equations • __ C3H8 + __ O2 __ CO2 + __ H2O • __ Ca2Si + __ Cl2 __ CaCl2 + __ SiCl4 • __ C7H5N3O6 __ N2 + __ CO + __ H2O + __ C • __ C2H2 + __ O2 __ CO2 + __ H2O • __ Fe(OH)2 + __ H2O2 __ Fe(OH)3 • __ FeS2 + __ Cl2 __ FeCl3 + __ S2Cl2 • __ Al + __ Hg(CH3COO)2 __ Al(CH3COO)3 + __ Hg • __ Fe2O3 + __ H2 __ Fe + __ H2O • __ NH3 + __ O2 __ NO + __ H2O Types of Chemical Reactions • Synthesis – A+B AB • Decomposition – AB A + B • Combustion – Burn in the presence of O2, to form dioxide gas, and other products **(CO2 + H2O) • Single Displacement – ACTIVITY SERIES – AB + C AC + B • Double Displacement – AB + CD AD + CB Predict the Product CaO + H2O H2SO3 + O2 CaCO3 KClO3 C6H10 + O2 C6H12O6 + O2 Al + CuCl2 Ca + KCl Na2SO4 + CaCl2 KCl + NaOH Ca(OH)2 H2SO4 CaO + CO2 KCl + O2 CO2 + H2O CO2 + H2O AlCl3 + Cu No Reaction NaCl + CaSO4 KOH + NaCl Identifying Redox Reactions Redox Redox Not Redox Redox Not Redox 2 KNO3(s) 2 KNO2(s) + O2(g) +1 -1 +1 -1 0 H2(g) + CuO(s) Cu(s) + H2O(l) 0 -2 +2 0 2(+1) -2 NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) +1 -1 +1 -1 +1 -1 2(+1) -2 H2(g) + Cl2(g) 2HCl(g) 0 0 +1 -1 SO3(g) + H2O(l) H2SO4(aq) +6 3(-2) 2(+1) -2 2(+1) -2 Balancing Redox Reactions • The following unbalanced equation represents a redox reaction that takes place in a basic solution containing KOH. Balance the redox reaction. Br2(l) + KOH(aq) KBr(aq) + KBrO3(aq) Br2(l) + KOH(aq) KBr(aq) + KBrO3(aq) Ionic Reaction: Br2 Br- + BrO30 -1 +5 3(-2)Reduction ½ Rxn: Br2 BrBr2 + 2e- 2Br5(Br2 + 2e- 2Br-) Oxidation ½ Rxn: Br2 BrO312OH- + Br2 2BrO3- + 6H2O + 10eCombined Rxn: 5Br2 + 12OH- + Br2 + 10e- 10Br- + 2BrO3- + 6H2O + 10e6Br2 + 12KOH 10KBr + 2KBrO3 + 6H2O 3Br2 + 6KOH 5KBr + KBrO3 + 3H2O Standard Reduction Potentials in Voltaic Cells Write the overall cell reaction and calculate the cell potential for a voltaic cell consisting of the following half-cells: an Iron electrode in an Iron (III) Nitrate solution, and a Silver electrode in a Silver(I) Nitrate solution. • Fe3+(aq)+3e-Fe(s) E0=-0.04V • Ag+(aq)+e-Ag(s) E0=+0.80V • E0cell= E0cathode- E0anode • E0cell= (+0.80 V)- (-0.04 V)= +0.84 V • E0cell= positive = spontaneous Acid/Base Properties • Strong Acids and Bases – Will ionize completely in a solvent • Weak Acids and Bases – Will ionize partially in a solvent • Buffer Systems – Solution containing a weak acid, and a salt of the weak acid • Acetic Acid and Sodium Acetate • Carbonic Acid and Bicarbonate Break Time Take a 10 minute break Mass-Mass Stoichiometry 3 Cu + 8 HNO3 3 Cu(NO3)2 + 4 H2O + 2NO • Copper Nitrate is used in creation of some light sensitive papers • Specialty photographic film • Your company needs 150 grams of Copper nitrate to fill an order. How many grams of Nitric Acid are needed to undergo reaction? • Step 3: Compute 150g Cu(NO3)2 1 mole 187.554g 8 mol HNO3 63.012 g 3 mol Cu(NO3)2 1 mole 134 g HNO3 = Gas Stoichiometry Xenon gas reacts with fluorine gas according to the shown reaction. If a researcher needs 3.14L of XeF6 for an experiment, what volumes of Xenon and Fluorine should be reacted? Assume all volumes are measured under the same temperatures and pressures. Xe (g) + 3 F2 (g) XeF6 (g) Gas Stoichiometry • Xenon 3.14L XeF6 1mole 1Xe 22.4L = 22.4L 1XeF6 1 mole 3.14L Xe • Fluorine 3.14L XeF6 1 mole 3 F2 22.4L = 22.4L 1 XeF6 1 mole 9.42L F2 Solution Stoichiometry • How many milliliters of 18.0M Sulfuric Acid are required to react with 250mL of 2.50M Aluminum Hydroxide? • H2SO4 + Al(OH)3 H2O + Al2(SO4)3 • 3 H2SO4 + 2 Al(OH)3 6 H2O + Al2(SO4)3 250mL Al(OH)3 1L 2.5 mol 3 H2SO4 1L 1000mL 1000mL 1 L 2 Al(OH)3 18.0 mol 1L 52.1 mL H2SO4 Titrations • In a titration, 27.4mL of 0.0154M Ba(OH)2 is added to a 20.0mL sample of HCl solution with unknown concentration until the equivalence point is reached. What is the molarity of the acid solution? 0.0154M Ba(OH)2 x 27.4mL Ba(OH)2 x 2 mol HCl x 1 = 1 1 mol Ba(OH)2 20.0mL 4.22 x 10-2 M HCl Limiting Reactant • The reaction of Ozone with Nitrogen Monoxide to form Oxygen and Nitrogen Dioxide in the atmosphere is responsible for the Ozone hole over Antarctica. • If 0.960g of Ozone reacts with 0.900g of Nitrogen Monoxide, how many grams of Nitrogen Dioxide are produced? Limiting Reactant 0.960g O3 1 mole 48g O3 1 NO2 44.0g NO2 1 O3 1 mole 0.880g NO2 0.900gNO 1 mole 30g O3 1 NO2 44.0g NO2 1 O3 1 mole 1.32g NO2 Break Time Take a 10 minute break Chemical Equilibrium • Chemical Equilibrium – Point in a reversible chemical reaction when the rate of the forward reaction equals the rate of the reverse reaction. – The concentrations of its products and reactants remain unchanged • Le Chatelier’s Principle – If a system at equilibrium is stressed, the equilibrium is shifted in the direction that relieves the stress How to Affect Equilibrium • Change in Pressure – Only affects reactions with gases – Increased pressure increases concentration – Decreased pressure decreases concentration • Change in Concentration – Of reactants or products. • Increase one- it moves to the other • Decrease one- it moves towards the one you lowered • Change in Temperature – Exothermic • Increase temperature will direct in reverse • Decrease temperature will direct forward – Endothermic • Increase temperature will direct forward • Decrease temperature will direct in reverse Equilibrium Constant nA + mB ↔ xC + yD K= [C]x[D]y [A]n[B]m Factors affecting Reaction Rates Rate Laws A chemical reaction is expressed by the balanced chemical equation A + 2B C Three reaction rate experiments yield the following data. Experiment Number Initial [A] Initial [B] Initial Rate of Formation of C 1 0.20 M 0.20 M 2.0 x 10-4 M/min 2 0.20 M 0.40 M 8.0 x 10-4 M/min 3 0.40 M 0.40 M 1.6 x 10-3 M/min What is the Rate Law for the Reaction? What is the Order of the reaction with respect to B? Rate Law for the Reaction A + 2B C R = k[A][B]2 Order of the Reaction with respect to B B is of a 2nd order reaction A is of a 1st order reaction Calculating pH and pOH pH + pOH = 14 pH = -log[H+] pOH = -log[OH-] • What is the pH of a 2.5x10-6M HNO3 solution? • pH = -log [2.5x10-6] • pH = 5.6 Break Time Take a 10 minute Break When we return… POST TEST Post-Test • You will have one and a half hours to complete the post-test • This test will include examples from all the competencies. • Scores will be posted on the Quia Website tomorrow as a class file. • Also to be posted- a reference key of the correct answers AND which competency and skill were covered for each question. Good Luck! When finished, turn in test to instructor, and you may leave.