2A Final Exam Review Worksheet. General Concepts (not meticulously exhaustive):

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1 2A Final Exam Review Worksheet General Concepts (not meticulously exhaustive): Density = mass / volume Terms: compound, mixture, element Isotopes o Isotope = occurs when the number of neutrons vary for a particular element. The number of protons do not vary. o Given any two of these variables, be able to solve for the third: weighted average atomic mass, isotopic mass, fractional abundance Counting protons, neutrons, and electrons in elements and ions Composition problems o Percent mass o Empirical formulas, molecular formulas Nomenclature: aqueous acids, molecular compounds, ionic compounds, straight-chained alkanes Balancing reactions o By inspection o Redox: reactions where oxidation states change Oxidized, Reduced, Ox Agent, Red Agent Half-Reaction Method of balancing Stoichiometry o For individual molecules o Reactions Stoichiometric calculations Writing reactions (net ionic, double, single, combustion, combination, decomposition, neutralization, precipitation) o Limiting reaction Stoichiometry problems where information related to moles is given for 2 or more reactants Combo with % Yield Amount unreacted o Titrations Stoichiometry problems involving molarity, M Moles needed to neutralize o Percent Yield Dilution (M 1 V 1 = M 2 V 2 & n 1 = n 2 ) Solubility Rules (will it precipitate?) Strong Acids and Bases vs. Weak Gas Laws o Combined Gas Laws (including Charles, Boyle, etc.) o Ideal Gas Law (& d = m/v & M = m/n) o Dalton s Law (mixture of 2 or more gases) General Problem Dalton over water Kinetic Theory of Gases Assumptions & Concepts o 5 assumptions o Temperature is proportional to kinetic energy. Two molecules at the same temperature will have the same average kinetic energy. o If two molecules are under the same conditions, the heavier molecule will travel slower

2 Energy equations o c = λν o E = hν = hc/λ o Rydberg equation (also know how to use it to calculate ionization energy, I) Quantum Numbers o Given a quantum number, determine all possible quantum numbers o Determine if a set of quantum numbers is allowable o Determine what set of quantum numbers are associated with a particular electron in an atom. Electron configuration o spdf shorthand notation o Orbital electron energy level diagram especially when generating an MO diagram or hybridization diagram. Periodic Trends o Radius, Z eff, shielding/screening, I, EA, EN o Know trends for elements, ions o Understand how trends of Z eff and screening/shielding relate to other trends such as r, I, EA, EN, etc. o Know shielding trend for orbitals (spdf) o Determine ΔEN (also most ionic, most covalent, most polar, most nonpolar) for a bond from Periodic Table Problems based on Lewis Structures o Draw Lewis structures and resonance structures o Find formal charge, ideal bond angles, electronic geometry, molecular geometry, polarity, BO (remember resonance), relative BL, relative BE, hybridization, number of σ bonds, number of π bonds MO diagrams o Draw diagram, label energy levels, fill in electrons for any homonuclear diatomic molecule or ion (no larger than Ne 2 ) o Understand concepts behind σ and π bonds o Paramagnetic or diamagnetic o Calculate BO Hybridization o Determine hybridization for any central atom o Draw hybridization schematics for sp, sp 2, and sp 3 for atoms (C as well as others) o Determine what hybrid orbitals overlap to form a bond o Determine the total number of σ and π bonds in a molecule (remember bond-line formulas) Questions (not necessarily representative of all possible questions): 1. If the density of aviation fuel is 1.77 lb/l, how many liters must be added to a tank to give 16,131 kg (1 kg= lb)? 2. Count the total number of protons, neutrons, and electrons: protons neutrons electrons 192 Ir 2+ NO + HSO 4

3 3. There are two stable isotopes of supposium (Su). Su-191 = u (27.30%) Su-194 = u (72.70%) Compute the atomic mass of supposium. 4. Name: A. SrI 2 (aq) B. CrCO 3 (s) C. HBr (aq) D. HNO 2 (aq) E. XeF 4 (g) F. HClO G. HClO 2 5. What is the charge on Z? Z(PO 4 ) 3 6. The monosaccaride ribose is found in biological systems. Combustion analysis shows that ribose contains 40.00% carbon, 6.714% hydrogen, and 53.29% oxygen. A. Calculate the empirical formula of ribose. B. If the molecular mass of ribose is g/mol what is the molecular formula of ribose? 7. Reactions A. Balance: HClO 4 + P 4 O 10 H 3 PO 4 + Cl 2 O 7 B.Which of the following represents a redox reaction? i) 2 H2(g) + O2(g) 2 H2O(l) ii) NH3(aq) + HCl(aq) NH4Cl(aq) iii) 2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s) iv) HBr(aq) + AgNO3(aq) HNO3(aq) + AgBr(s) v) 2 H2O2(aq) 2 H2O(l) + O2(g) C. Write the combustion reaction for hexane 8. S 8 (s) + OH (aq) S 2 O 3 2- (aq) + S 2- (aq) + H 2 O (l) A. What is oxidized? What is oxidizing agent? B. Balance in basic conditions. 9. For question 7A above A. If there is 10.0 g of P 4 O 10, find the mass of phosphoric acid formed. B. If there is also 10.0 g of perchloric acid, find the mass of phosphoric acid formed. C. Considering A & B, how much of the excess reactant remains after the reaction is complete. D. Find the number of phosphorus atoms in 10.0 g of P 4 O 10. E. If the mass of phosphoric acid formed was 1.00e-3, find the percent yield. 10. With ml of an acid at 2.0 M, what final vol. is necessary in order to dilute the acid to 0.50 M? ml of 2.00 M sulfuric acid neutralizes with what mass of potassium hydroxide? 12. A. What are the products to the following reaction that occurs in solution? (NH 4 ) 2 S + Al(C 2 H 3 O 2 ) 3? B. Which will ppt? Sr(NO 3 ) 2, BaSO 4, BaS, AgBr, AuBr 13. What are all the strong acids and strong bases from Chp 5? Is HClO a strong acid? moles of helium gas at 1.0 atm is in a 6.0 L container at 27 C. All the helium gas is then transferred to a 12.0 L container at 327 C. What is the final pressure? g of an ideal gas of molecular weight = 30.5 g/mol is confined at a pressure of 133 mmhg. The density of the gas is g/l. Compute the temperature of the gas in degrees Celsius.

4 16. A tank contains grams of oxygen and grams of helium at a total pressure of 7.00 atmospheres. A. What are the total moles of gas in the tank? B. What is the partial pressure of O 2? C. What is the partial pressure of He? 17. A. Fill in the blanks: n i n f E λ (nm) ν (MHz) 2 3 B. Would a wavelength of 600 nm be higher or lower energy than part A? 18. Label the electrons (A, B, C) from the table in the electron configuration below. Electron Label n l m l m s A ½ B ½ C ½ 19. Fill in the BLANKS with the correct electron configuration (spdf condensed) or correct neutral element. Element Electron Configuration Bi 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 5d 9 4f Circle the correct answer in the table below. Question: Answer? Which element has the lower first ionization energy? B O Which orbital is better at shielding (screening)? p d The oxide of which element can react with both acids and bases? Ca Al Which chemical species is a better reducing agent? Li F Which bond is more covalent? CO BO In the atom of phosphorus, total spin (the sum of electron spin quantum numbers m s ) is 3/2 0 Which species has the smaller radius? Na Mg The structure of aspirin is given below. a. Which set of hybrid orbitals best describes the (a-b) C-O bond in aspirin? b. What is the approximate bond angle around the O labeled a? c. What is the bond order of the (a-b) C-O bond? d. Is this molecule polar or nonpolar? e. What is the geometry around the oxygen atom labeled a? f. What is the hybridization of the carbon atom marked b? g. What s the molecular formula of aspirin? 22. Draw the 2 possible Lewis structures (i.e., 2 most likely structures) of thiocyanide (SCN ). Assign formal charges to all elements in all structures. Circles the most probable structure bases on formal charges.

5 23. Fill in the following table for the best Lewis structure. Determine formal charge and oxidation state for the underlined elements. Molecule Electronic Molecular Bond Polar or Hybridization Charge(s) State Bonds Formal Oxidation Total σ Total π Geometry Geometry Angles Nonpolar Bonds ClF 3 ClCN BH 3 XeOF 4 OF Draw the energy diagram for an sp 3 hybridized N atom, then fill in the electrons. Describe what each hybridized orbital represents. 25. Draw the MO diagram for O 2 + labelling all the energy levels. Determine the BO and magnetism. 26. What is the CO bond order of the carbonate ion? Answers (hopefully they are all correct): x 104 L 2. Protons neutrons electrons 192 Ir NO HSO u 4. Strontium iodide, chromium (II) carbonate, hydrobromic acid, nitrous acid, xenon tetrafluoride, hypochlorous acid, clorous acid CH 2 O, C 5 H 10 O 5 7. A. 12 HClO 4 + P 4 O 10 4 H 3 PO Cl 2 O 7 B. i and v C. 2 C 6 H O 2 à 12 CO H2O 8. A. S or S 8 B. 12 OH (aq) + S 8 (s) 2 S 2 O 3 2- (aq) + 4 S 2- (aq) + 6 H 2 O (l) g, 3.25 g, 7.6 g, 8.49e22 atoms, % ml g 12. A. 3 (NH 4 ) 2 S (aq) + 2 Al(C 2 H 3 O 2 ) 3 (aq) 6 NH 4 C 2 H 3 O 2 (aq) + Al 2 S 3 (s) B. aq, s, aq, s, aq 13. SA: HClO 3, HClO 4, HCl, HBr, HI, HNO 3, H 2 SO 4 SB: KOH, NaOH, LiOH, RbOH, CsOH, Ca(OH) 2, Sr(OH) 2, Ba(OH) 2

6 HClO is a weak acid atm C mol, 3.00 atm, 4.00 atm 17. A. n i n f E λ (nm) ν (MHz) e e8 B. Higher 18. A = #2, B = #3, C = # Element Electron Configuration Bi [Xe]6s 2 5d 10 4f 14 6p 3 Pt 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 5d 9 4f B, p, Al, Li, CO, 3/2, Mg sp 2 (C) sp 3 (O), 109.5, 1, polar, bent, sp 2, C 9 H 8 O (not good!) 23. Molecule Electronic Molecular Bond Angles Polar or Hybridization Nonpolar Formal Charge Oxidation State σ Bonds π Bonds ClF 3 Trigonal- Bipyramidal T-shape 90º polar sp 3 d ClCN Linear Linear 180º polar sp BH 3 Trigonal Planar Trigonal Planar 120º nonpolar sp XeOF 4 Octahedral Square Pyramidal 90º polar sp 3 d OF 2 Tetrahedral Bent 109.5º polar sp

7 24. E 2p 2s sp 3 unhybridized hybridized The first hybridized orbital represents the lone pair of electrons on N. The next three hybridized orbitals represent potential sigma bonds with other elements. 25. BO = 2.5, paramagnetic (MO diagram below) σ 2p * 2p π 2p * π 2p 2p E σ 2p σ 2s * 2s 2s σ 2s