Chemistry I Course Review Key


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Chemistry I Course Review Key

  1. 1. Chemistry I Course Review Key The Basics 1. a) Goggles must be worn any time there is an open flame or hazardous chemicals in the lab. b) Chemicals should be handled with care; lids should be returned when a bottle is finished; chemicals should never be eaten or tasted unless directed by the teacher. Students should pour form larger stock bottles into smaller containers that will be used in the lab. Any leftover waster should be disposed of according to teacher direction, but NEVER poured back into the stock solution. c) When heating a chemical in a test tube, the open end of the test tube should be aimed towards a wall, away from any people. d) Report cuts and burns to a teacher immediately who will start first aid if necessary and contact the health room. e) If an odor is to be detected, the fumes should be wafted towards the nose, not snorted in a large amount. f) If a fire alarm sounds during lab, all electrical equipment, water, and gas should be shut off before the room is evacuated as normal. 2. a) Football fields can be measured in meters. A paperclip can be measured in cm. Length should best be measured with a metric ruler or meter stick. b) The volume of a bottle of soda could be measured in liters (2L soda) or mL (20oz size) with a graduated cylinder. Raindrops can be measured using a graduated cylinder mL A rectangular solid can be measured with a metric ruler. c) The mass of a human being would be measured in kilograms on a balance. A penny would also be measured on a balance however it would be measured on a balance however it would be measured in grams. d) Temperature should best be measured with a thermometer. 3. a) 80.2 b) 2.41.3 x 1023 c) 1.3 x 1023 d) 1.8 x 106 e) 0.01628 f) 0.0012 4. a) kilo- b) hector- c) deka- d) deci- e) centi- f) milli- 5. a) 0.0045 kg b) 8.5 x 105 mm c) 5.4 x 105 mL d) 0.64512 L e) 3.25 x 10-4 mm 6. Precision is how close a group of measurements are to each other; accuracy is how close a measurement is to the accepted or true value. The Atom 7. a) Each shell (energy level) would hold 2,8,18,32 electrons respectively. Each subshell would hold s(2), p(6), d(10), f(14). b) i) 1s22s2p63s1; Lewis Dot Structure (LDS) is Na with a single dot. ii) 1s22s22p3; LDS is N with one pair of dots and three single dots. iii) 1s22s22p63s23p64s23d104p5; LDS is Br with a single dot and three pairs. c) An ion is a atom or molecule with an overall positive or negative charge. d) A sodium atom becomes an ion by losing its single outer shell electron. It would therefore have a positive one (+1) charge. e) A sulfur atom becomes an ion by gaining two electrons to complete its outer shell. It would therefore have a negative two (-2) charge.
  2. 2. Chemistry I Course Review Key f) Carbon-14 has 6 protons, 6 electrons and 8 neutrons. g) U-238 has 146 neutrons. h) Dalton’s model consisted of solid spheres of matter. Thomson’s model had a ball of positively charged matter with negatively charged “bits” inside of it. Rutherford/Bohr’s model had a dense positive core (the nucleus) with electrons in perfect circular orbits around it. Schrodinger’s model had a dense positive core with electrons orbiting in orbital’s (three- dimensional, mathematically-defined zones of space.) 8. a) Natural radioactivity is radiation that exists on its own in nature. Induced radioactivity is radiation that has been created in a laboratory (man-made). b) The three basic types of radiation are: alpha (α) in which a helium nucleus (alpha particle) breaks off from the unstable atom; beta (β) in which an electron produced from the breakup of a neutron (a beta particle) is shot from the nucleus; and gamma (γ) in which a burst of high energy light (a gamma ray) is emitted from the nucleus. c) Penetrating ability: least is alpha, then beta, and gamma has the most. d) Fission is when a large unstable nucleus splits into two new nuclei. Fusion is when two smaller nuclei are fused together to make a single nucleus. e) An isotope is a group of elements with the same number of protons (same element) and the same number of neutrons (same mass). f) Half-life is the time it takes for half of radioactive sample to decay. g) 8.25 x 10 -27 g h) 52.00 amu The Periodic Table 9. a) The periodic table is arranged such that the elements are in order of increasing atomic number, and elements of similar chemical properties are grouped in columns together. This is different than Mendeleev’s table which was organized by atomic mass. b) A group is a vertical column on the periodic table, containing elements of similar chemical properties. A period is a horizontal row on the periodic table. c) The metals are to the left and below the “stair-step” on the periodic table. The nonmetals are to the right and above. d) Metals: shiny; good conductors of heat & electricity; malleable & ductile. Nonmetals: dull; insulators of heat & electricity; brittle. Metalloids: elements with some metal properties and some nonmetal properties e) Group 1: alkali metals; Group 2: alkaline earth metals; Group 17: halogens; Group 18: noble gases; Groups 3-12: transition metals f) Ionization energy is the amount of energy required to remove the outer most electron from an atom. Electronegativity is a measure of an atom’s ability to draw electrons towards itself in a covalent bond. g) Electronegativity increases across a period and decreases down a family. Ionization energy does the same thing. h) Elements in a family have similar chemical properties. i) Atomic radius decreases across a period and increases down a family. j) V has the highest ionization energy. k) Fr is the most metallic of all the elements. It has the lowest ionization energy, the lowest electro negativity, and is the most reactive metal. It has the largest atomic radius. F is the most non-metallic of all the elements. It has the highest ionization energy and the highest electronegative and is the most reactive non-metal. These two elects are the “most” of their group (metal versus non-metal).
  3. 3. Chemistry I Course Review Key l) Even though both Be and He have two outer shell electrons, Helium’s electrons fill the first energy level (shell) completely while Be has two more electrons that are in the next sub shell causing an incomplete outermost shell. Compounds and Bonding 10. a) An ionic bond is the electrostatic attraction between two oppositely charged ions. A covalent bond is a shared pair(s) of electrons between two atoms. They are different chiefly in that an ionic bond doesn’t need to exist in order for the atoms to have a complete outer shell (they already have transferred electrons) but a covalent bond must stay whole for all of the atoms to keep their stable full outer shells. b) Metallic bonds are bonds that occurs the result of free floating valence electrons for positively charged metal ions. Metallic bonds help explain why metals conduct heat and electricity so easily as the heat (increased motion) moves easily from one electron to another. c) i) potassium sulfate ii) aluminum chloride hexahydrate iii) hydrobromic acid iv) tin(IV) nitrate v) carbon monoxide vi) nitrous acid d) i) Ag3PO4 ii) CCl4 iii) Fe2O3 iv) K2CrO4 v) Cu(NO3)2 x 3H2O vi) H2SO4 e) A roman numeral in a chemical’s name tells the charge on the positive ion (ex: “iron (III) oxide” means that the iron ion’s charge is +3). f) i) ii) O=C=O iii) g) i) linear ii) tetrahedral iii) bent Matter and Energy 11. a) 4650 J b) 360 g (358.5 g rounded to two sig figs) c) Copper would be heated faster than water of the same mass from room temp to 56 degrees C because metals (like copper) have smaller specific heats that water does, so it takes less energy (and therefore less time) to heat them. d) Heat of fusion is the amount of heat energy needed to melt 1 g of substance. Heat of vaporization is the amount of heat energy needed to vaporize 1 g of a substance. e) 4540 J (4536 J rounded to 3 sig figs) f) Temperature is the average kinetic energy of all the particles in a sample. Absolute zero is the theoretical lowest temperature possible (O K). g) Temperature is an average kinetic energy of the particles, where heat is the total kinetic energy of the particles. h) i) endothermic ii) endothermic iii) exothermic iv) exothermic i) Intensive properties are ones that do not depend on the size of the sample (ex: density, freezing point) while extensive properties are ones that do depend on the size of the sample (ex: mass, volume). j) Salt and sand could be separated by dissolving the salt in water, filtering out the sand, then boiling the water away from the salt. Alcohol and water could be separated by distillation (boiling the alcohol away form the water and collecting and recondensing the vapors).
  4. 4. Chemistry I Course Review Key The Mole 12. a) i) 110.26 g/mol ii) 253 g/mol iii) 342.3 g/mol b) i) 29.1% K ii) 25.3% K iii) 28.1% K c) i) 0.136 mol K2S ii) 0.0593 mol Ba(SCN)2 iii) 0.0438 molAl2(SO4)3 d) 3.39 x 1024 molecules O2 e) 126 L O2 f) Sn3N2 Chemical Reactions 13. a) i) 2,2,2,1 ii)2,2,3 iii)1,6,2,3 b) i) single replacement ii) decomposition iii) double replacement(ionic) c) i) Zinc+ copper(II) sulfate  copper+ zinc sulfate Zn+ CuSO4  Cu + ZnSO4 ii) lead(II) nitrate+ sodium sulfate sodium nitrate+ lead (II) sulfate Pb(NO3)2 + Na2SO4 2 NaNO3+ PbSO4 iii) ethane+ oxygen  carbon dioxide+ water 2 C2H6+ 7 O2  4 CO2+ 6 H2O Stoichiometry 14. a) i) 10 mol NaCl ii) 5 formula units Na2SO4 b) i) 9 molecules CO2 ii) 25 mol O2 iii) 13 L CO2 c) 24.9 g MgO d) 4.3 g Al2O3 e) 22.8 g PbI2; lead(II) nitrate is the limiting reactant Acids, Bases, and Salts 15. a) i) S ii) A iii) B iv) A v) B vi) B vii) S viii) S b) A solution’s acidity (or basicity) can be generally tested by litmus paper (litmus turning red indicates an acid, litmus turning blue indicates a base). More specifically, pH paper (or a pH meter) can be used to determine the solution’s pH (pH below 7 is acidic, above 7 is basic). c) A strong acid ionizes 100% in water. A weak acid ionizes less than 100%. d) When an acid and a base react, the reaction is called a neutralization reaction, and the products will be water and a salt. Gas Laws 16. a) Pressure is the force applied per unit area. b) At constant pressure, temperature and volume are directly proportional (if one goes up the other goes up). This is Charles’s Law. c) At constant temperature, pressure and volume are inversely proportional (if goes up the other goes down). This is Boyle’s Law. d) A constant volume, pressure and temperature are directly proportional (if one goes up the other goes up). This is Gay-Lussac’s Law. e) PV = nRT f) V2 = 1.10 L g) V2 = 0.549 L h) T2 = 526 K
  5. 5. Chemistry I Course Review Key Solutions 17. a) A solution is a homogeneous mixture. A solute is the substance being dissolved in a solution. A solvent is the substance that does the dissolving. In salt water, salt is the solute and water is the solvent. b) To make a solid dissolve faster in a liquid you could: stir the mixture; heat the mixture; grind up the solid into smaller pieces. c) Molarity measures the concentration of a solution; specifically it measure the number of moles of solute in every liter of solution. It’s units are “molar”, M, or mol/L. d) 2.5 M CuSO4 e) 4.28 M NaCl f) 2 mol CaCl2 (1.75 mol rounded to 1 sig fig) g) Solutions that are high in electrolytes will conduct electricity. If a solution does not contain dissolved ions then it will not conduct electricity. Molten ionic compounds (which may not be true solutions) will also conduct electricity.