Chemistry 530 Midterm Review Exam on Monday Dec 16 at 8:30 Section I = 75 pts Consists of 75 multiple choice questions worth 1 pt. each Questions cover all material covered during the second semester Questions will be similar to multiple choice problems in the book and review guides on-line Practicing the review guides is the best approach; answers will be posted on-line Section II = 95 pts Consists of 19 short answer problems totaling 95 points Questions cover the whole semester Examples of types of questions o Metric Conversions o Volume Calculations o Percent Composition o Atomic Mass o Electron configuration o Nomenclature o Balancing Equations o Predicting the products of a reactions o Identifying types of reactions o Mole Conversions o Molar Mass of a compound o Molar Mass of a gas at STP o Density of a gas at STP o Empirical & Molecular Formula Study approach First, read through your notes. Once thoroughly and once more quickly. Go through the review packet and make sure you are comfortable with all of the terms and how to do problems Do the review packets for help with multiple choice Do questions on old tests for practicing written problems Make sure you have practiced AT LEAST one of the types of example problems Chapter 1 – Introduction to Chemistry Chemistry: the branch of science that studies the composition and properties of matter. Scientific Method: o Observation o Hypothesis o Controlled Experiment Theory versus Natural Law Prerequisite Science Skills Rules for Significant Figures: 1) All non-zero digits are significant. 2) Zeros are significant only when they are between two non-zero digits or if they occur after a decimal point and after a non-zero digit. 3) In multiplication or division, you cannot end up with more significant figures than you started with. 4) In addition or subtraction, you cannot have more digits to the right of the decimal than you started with. Exponential numbers Scientific Notation = D.DD x 10n where 1.00 < D.DD < 9.99 Prerequisite Science Skills Practice Problems 1. Circle which of these measurements is NOT uncertain? 67 g 4.5 mL 457 K 22 people 6.7 x 10 11 moles 2. Convert the following into standard notation: -5 4.89 x 10 nm= 2 7.9 x 10 mm = 3. Convert the following into scientific notation: 0.00056 mg = 78,341 kg = 4. Give the number of significant figures in each of these measurements: 46 crucibles = 607 g = 0.00900 mL = 4.90 x 10 -5 s = 5. Subtract 45.6 from 67.89 and round off the answer. Answer = = 6. Multiply 240 by 2.10 and round off the answer. Answer = Chapter 2 – The Metric System Units: Unit Length Mass Volume Time Temperature Amount Energy Metric Unit Conversions Prefix Symbol kilok centic millim microμ nano- n Metric m g L s C mol cal SI m kg L s K mol J Conversion Factor 1 km = 1000 m 1 cm = 0.01 m 1 mm = 0.001 m 1 μm = 0.000001 m 1 nm = 0.000000001 m Conversions 1000 g = 1 kg K = C = 273.15 cal = 4.184 J Percent = % = Part / Total x 100 Volume = length x width x height Volume by displacement Density = Mass / Volume = M / V Temperature o F = 1.8 C + 32 o C = ( F – 32 ) / 1.8 o K = C = 273 Chapter 2 Practice Problems 7. Make the following unit conversions: 5 g into kg 40 mL into L 319 nm into cm 316 K into Celsius 8. A student is trying to determine the identity of an unknown metal. He finds that its mass is 20.0 g and its volume is 1.0 mL. The density of the metal is: Known Densities of Metals Gold Mercury Lead Silver Copper Aluminum 3 19.3 g/cm 3 13.6 g/cm 3 11.4 g/cm 3 10.5 g/cm 3 8.9 g/cm 3 2.7 g/cm The metal that the student has is: 9. An alloy contains 12 parts platinum and 4 parts gold. Find the percent of platinum and gold in this alloy. Chapter 3 – Matter and Energy Element: a pure substance that cannot be broken down by a chemical reaction. Compound: a pure substance that can be broken down into two or more substances by a chemical reaction. Mixtures: o Homogeneous (the same properties throughout) o Heterogeneous (different properties throughout). Physical States: Solid (s), Liquid (l), Gas (g), Aqueous (aq). Chemical vs. Physical properties and changes. Metals: Non-Metals: Semi-metals or Metalloids: Law of Conservation of Mass: Matter can neither be created nor destroyed. Law of Conservation of Energy: Energy can neither be created nor destroyed. Potential vs. Kinetic Energy Chapter 3 Practice Problems 10. Give examples of the following: Element = Compound = Homogeneous mixture = Heterogeneous mixture = 11. How many atoms are in a glucose molecule, Al (C2H3O2 ) 3 ? # Al = __________ # C = ___________ #H = ___________ # O = ___________ 12. Name the following phase changes: Solid Liquid = Liquid Gas = Gas Solid = Solid Gas = Gas Liquid = Liquid Solid = 13. Consider a glass of water. What are three of its physical properties? What are three of its chemical properties? 14. What are three properties of a gas? Three properties of a liquid? Three properties of a solid? Chapter 4 – Models of the Atom Atom + o proton (p , 1 amu) o o neutron (n , 1 amu) o electron (e , 0 amu) Basic idea of theories of the atom Bohr models of the atom Atomic notation Atomic number Mass number Isotopes o Atomic mass calculations based on isotope abundance Electromagnetic spectrum Quantum mechanical model of atom o orbitals (n = 1, 2, 3, 4 …) o sub-orbitals (s, p, d, f) know how many electrons each holds know shapes of s and p orbitals electron configuration for atoms and ions o know order of filling Heisenberg’s Uncertainty Principle Chapter #4 -Practice Problems: 15. Complete the following table: Symbol Atomic Number Mass Number Protons Al Neutrons 14 33 75 19 9 16. Write the atomic symbol of an element which has 6 protons, 6 electrons and 7 neutrons. 17. Copper has two natural isotopes: Cu-63 (62.930 amu) and Cu-65 (64.928 amu). Calculate the atomic mass of copper given the abundance of Cu-63 is 69.09%. 18. Give the maximum number of electrons for the following orbitals: s = ____________; Shape of s orbital = _______________ p = ____________; Shape of p orbital = _______________ d = ____________ f = ____________ 19. Give the maximum number of electrons for the following energy levels: 1st= ____________ 2nd= ____________ 3rd= ____________ 4th= ____________ 20. Write the electron configurations for: Br = 3 N = __________________________________ Pt = __________________________________ + Cu = __________________________________ Chapter 5 – The Periodic Table Periodic table o groups (alkali, alkaline earth metals, halogens, noble gases) Electrons o periods o representative elements v. transition elements Periodicity (periodic trends) - know how each increases/decreases, and what each is o atomic radius o metallic character (same as atomic radius) o ionization energy o electronegativity Valence electrons Lewis dot structures Chapter #5 - Practice Problems: 21. How many electrons are in the valence shells of these atoms and ions? Write the electron configuration using Noble Gas configuration. Cl = ____ valance electrons, o Mg = ____ valance electrons, o Cr Se 2- Electron configuration = = ____ valance electrons, o Electron configuration = = ____ valance electrons, o Electron configuration = Zn 2+ o Electron configuration = = ____ valance electrons, Electron configuration = 22. Draw Lewis electron-dot structures of the atoms and ions given above. Cl Mg Se 2- Zn 2+ Cr 23. Put these atoms and ions in order from lowest to highest atomic radius. 22+ Ca Ag Se Ba O 24. Circle the atom or ion with the highest ionization energy in each pair. 2+ – Zn or Zn Si or S F or F 25. Put these atoms and ions in order from highest to lowest electronegativity. + 3I Fr Cu N P 26. Name the group to which each of these atoms belongs. F = Na = Mg = Fe = Pb = Chapter 6: Language of Chemistry Ions: o Cation = a positively charged ion. o Anion = a negatively charged ion. Ions are formed by gaining or losing electrons. Know monoatomic ion’s name, formula and charge (Use location on Periodic Table ) Memorize polyatomic ion’s name, formula and charge Forming Ionic Compounds - Cross over the charge, not the + or Example: Magnesium is a 2+ cation = Mg 2+. Nitrate is a 1- anion = NO3 -. The chemical formula is Mg(NO3)2. Nomenclature: I. Binary Ionic Compounds (metal + non-metal) Name the metal cation first. Name the non-metal anion second, change the suffix to –ide. Example: CaCl2 is calcium chloride. II. Binary Ionic Compounds with a metal of variable charge (metal + non-metal) Name the metal cation first. Give the charge on the metal using Roman Numerals (I), (II), (III), (IV), (V). Name the non-metal anion second, change the suffix to –ide. Example: Fe2O3 is iron (III) oxide. III. Ternary Ionic Compounds (containing polyatomic ions.) Name the cation first, using Roman Numerals if necessary. Name the anion second, do not change the suffix if it is a polyatomic ion. Examples: Ni3(PO4)2 is nickel (II) phosphate; NH4I is ammonium iodide. IV. Binary Molecular Compounds (non-metal + non-metal) Name the most metallic element first (the one furthest to the left table). Name the least metallic element second, change the suffix to –ide. Use prefixes to indicate the number and type of each atom (mono-, di-, tri-, tetra- penta-, hexa-, hepta-, octa-, nona-). Example: SF6 is sulfur hexafluoride (or monosulfur hexafluoride). V. Acids- Can often be recognized by hydrogen beginning a formula. Binary acid – To name 1. changing the word hydrogen to hydro2. change the ending: -ide to –ic acid Ternary oxyacids - To name 1. drop the word hydrogen, 2. change the ending: –ate changes to –ic acid. –ite, changes to –ous acid. You should be able to name these five common acids: HCl HNO3 H2SO4 H3PO4 HC2H3O2 VI. Bases - Can often be recognized by hydrogen ending a formula. Bases are named just like other ternary ionic compounds (see III); the exception is NH3, which is ammonia. Chapter 6 Practice Problems 27. Name the following compounds: CCl4 MgCr2O7 NiSO4 NaOH H2SO4 28. Write formula for the following compounds: Zinc sulfite Silicon dioxide Iron (II) phosphide Potassium dichromate Ammonium nitrate Chapter 7: Chemical Reactions You should be able to predict and balance equations: Make sure there are the same number of atoms of each type on each side by using coefficients. Types of Reactions: A. Combination Reactions Two or more reactants One product 2Mg(s) + N2(g) 2MgN(s) B. Decomposition Reactions One reactant Two or more products 2NaHCO3(s) Na2CO3(s) + H2O(l) + CO2(g) Na2CO3(s) Na2O(s) + CO2(g) 2NaO(s) 2Na(s) + O2(g) C. Single-replacement Reactions One element replaces another element in a compound. 2Na(s) + ZnCl2(aq) 2NaCl(aq) + Zn(s) Predictable: Consult the activity series More active metals can replace less active ones. D. Double-replacement Reactions Two ionic compounds exchange partner ions, forming two new compounds. 2AgNO3(aq) + CuCl2(aq) 2AgCl(s) + Cu(NO3)2(aq) Predictable: Swap the ions to make two neutral compounds. Consult the solubility rules to determine if the products are solid (s) or aqueous (aq). E. Neutralization Reaction Acid and Base produce water and a salt (ionic compound) Chapter 7 Practice Problems 29. For the following reactions: 1. Predict the products of the following reactions 2. Indicate physical states for double- replacement reactions (consult the Solubility Rules). 3. Balance the chemical equations. 4. Indicate the type of chemical reaction for each a. O2(g) Na(s) + Type: b. H2O(l) Ag(s) + Type: c. MgBr2(aq) + K2SO4(aq) Type: d. Al(s) + Pb(NO3)2(aq) Type: e. MgCO3(s) Type: f. H2O(aq) + KMnO4(aq) Type: Chapter 8 – The Mole Concept 23 Avogadro’s Number = 6.02 x 10 particles (atoms, ions, formula units or molecules) Mole Molar Mass = MM = grams (Get this from the Periodic Table) Molar Volume of a gas at STP = 22.4 Liters Density of a gas @ STP = Molar Mass / Molar Volume = MM / 22.4 L = g/L Percent Composition: % Element = Molar Mass of Element / Molar mass of Compound x 100 Empirical Formula: Gives the lowest whole number ratio of atoms in a compound. Molecular Formula: Either the same as the empirical formula, or a simple whole-number multiple of it Chapter 8 Practice Problems 30. How many grams are in 1.204 x 10 24 molecules of calcium hydroxide, Ca(OH)2 (MW = 74g/mol)? 31. How many moles are in 11.2 L of methane (CH4) gas? 32. Calculate the percent composition of heptane, C7H16. 33. Calculate the molar mass for Freon-12 if its density is 5.40 g/L at STP. 33. Nicotine has a molar mass of 160 g / mole. If the percent composition is 74.0 % C, 8.7 % H, and 17.3 % N, what is the molecular formula of nicotine? (HINT: Determine empirical formula first)