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2010-2011 Chemistry SOL Blitz

2010-2011 Chemistry SOL Blitz. Question #1. Which of the following atoms contains 30 protons, 40 neutrons and 28 electrons? A: 70 Zn +2 B: 70 Zn -2 C: 40 Zn +2 D: 30 Zr -2. Answer to Q#1. Letter A: 70 Zn +2 is the answer. Why? The format for chemical symbols is A X charge

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2010-2011 Chemistry SOL Blitz

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  1. 2010-2011 Chemistry SOL Blitz

  2. Question #1 • Which of the following atoms contains 30 protons, 40 neutrons and 28 electrons? • A: 70 Zn+2 • B: 70 Zn-2 • C: 40 Zn+2 • D: 30 Zr-2

  3. Answer to Q#1 • Letter A: 70 Zn+2 is the answer. • Why? The format for chemical symbols is A Xcharge z • Remember, A = mass, which equals protons + neutrons • Z = atomic number = protons • Charge = protons – electrons

  4. Question #2 • The element boron has only two stable isotopes. One stable isotope has a mass number of 10 and the other has a mass number of 11. Which of the following could be the atomic weight of the element? • A: 9.5 • B: 10.8 • C: 11.7 • D: 12.4

  5. Answer to Q#2 • Letter B: 10.8 is the answer • Why? The mass of an element on the periodic table is the weighted average of all the isotopes of that element

  6. Question #3 • An atom of Argon—40 contains— • A: 18 protons and 18 neutrons • B: 18 protons and 22 neutrons • C: 18 protons and 40 neutrons • D: 20 protons and 20 neutrons

  7. Answer to Q#3 • Letter B: 18 protons and 22 neutrons • Why? The 40 in Argon-40 is the mass of the isotope • Remember mass = protons + neutrons (electrons have no mass) • Argon has an atomic number of 18, so there 18 protons

  8. Isotope/ Ion Quick Review • Isotopes of an element have the same atomic number (protons) but different masses (hence different neutrons) • Both protons and neutrons have a mass of 1 • Electron’s mass is not taken into account in the mass of an atom • Ions are anything with an electrical charge • Positively charged ions have lost electrons • Negatively charged ions have gained electrons

  9. Question #4 • A scientist comparing K and Ca would find that K has a— • A: lower electronegativity and a smaller atomic radius • B: higher electronegativity and a smaller atomic radius • C: lower electronegativity and a larger radius • D: higher electronegativity and a larger atomic radius

  10. Answer to Q#4 • Letter C: lower electronegativity and a larger atomic radius • Why? Electronegativity gets higher as you go across a period and atomic radius gets smaller as you go across a period • K is farther left so it must have a lower electronegativity and larger atomic radius

  11. Question #5 • Which of the following elements is the most reactive? • A: Cs • B: Sr • C: Mg • D: Rb

  12. Answer to Q#5 • Letter A: Cs • Why? All these elements are metals—the most reactive metals are the largest • Atomic radius gets larger as you go down a group • Cs is farthest down so it is the largest and most reactive

  13. Trends Quick Review • Trends as you go down a group: larger atomic radius, lower electronegativity, lower and ionization energy (easier to lose an electron) • Trends as you go across a period: smaller atomic radius, higher electronegativity, and higher ionization energy (harder to lose an electron) • Remember IE is the energy it takes to lose an electron • Electronegativity is the ability to gain an electron

  14. Quick Review Continued • Metal reactivity: Largest metals = most reactive metals. • Remember metals like to lose electrons • Non-metal reactivity: smallest non-metals = most reactive non-metals. • Remember non-metals like gain electrons • Noble gases are non-reactive—they have a full valence shell

  15. Question #6 • A bond between an element of group 2 and an element of group 17 will be: • A: ionic • B: Nonpolar covalent • C: Polar covalent • D: Metallic

  16. Answer to Q#6 • Letter A: Ionic • Why? Group 2 elements are metals (also known as alkaline earth metals) and group 17 (or 7) elements are non-metals (also known as halogens) • Metals + non-metals = ionic bonding

  17. Bonding Quick Review • Covalent bonding = sharing of electrons between non-metals • Ionic bonding = transferring of electrons between metal + non-metal • Nonpolar covalent bond = equal sharing of electrons between non-metals • Polar covalent bond = unequal sharing of electrons between non-metals

  18. Question #7 • What is the name for Cu2S? • A: Copper sulfide • B: Copper (I) sulfide • C: Dicopper sulfide • D: Dicopper monosulfide

  19. Answer to Q#7 • Letter B: Copper (I) sulfide • Why? Copper is a transition (d block) metal, so you must use roman numerals to indicate its charge • Look behind S for the charge of Cu. • Charge is +1 so copper (I) sulfide

  20. Question #8 • Which of the following is the formula for carbonic acid? • A: HC • B: HCO • C: HO • D: H2CO3

  21. Answer to Q#8 • Letter D: H2CO3 • Why? It’s an acid so H must come first. Carbonic = carbonate = CO3-2 • H+1 + CO3-2 = H2CO3

  22. Question #9 • What is the molecular formula of tetraphosphorus decoxide? • A: PO • B: P4O • C: P4O10 • D: PO10

  23. Answer to Q#9 • Letter C: P4O10 • Why? Tetra = 4 and deca = 10 • So P4O10 • Remember, when using prefixes don’t switch—simply write what’s given

  24. Naming Quick Review • Must use roman numerals to indicate charge of a transition metal • Only use prefixes when the compound is all non-metals • If an acid has hydro prefix then it’s H+element • If no hydro prefix for an acid then it’s H+polyatomic

  25. Question #10 ___C3H4 + ___O2 ___CO2 + ___H2O • When the equation above is balanced, what is the sum of the coefficients? • A: 4 • B: 5 • C: 8 • D: 10

  26. Answer to Q10 • Letter D: 10 • Why? C3H4 + 4O2 3CO2 + 2H2O; so 1+4+3+2 = 10 • Don’t forget the law of conservation of mass says the reactants side = products side

  27. Question #11 • Which of the following is an example of a decomposition reaction? • A: 2AgCl  2Ag + Cl2 • B: CuO + H2O  Cu(OH)2 • C: AgCl + Mg  MgCl2 + Ag • D: HCl + Na(OH)  H2O + NaCl

  28. Answer to Q #11 • Letter A: 2AgCl  2Ag + Cl2 • Why? Decomposition is when you start with one reactant and break into 2 products • Letter B = synthesis; letter C = single replacement and letter D = neutralization reaction

  29. Question #12 • 12 x 403 = • What is the answer to the above problem expressed with proper sig figs? • A: 5,000 • B: 4800 • C: 4830 • D: 4836

  30. Answer to Q#12 • Letter B: 4800 • Why? When multiplying or dividing, you use lowest # of sig figs for your answer • 12 only has two sig figs, so your answer can only have two

  31. Question #13 • How many atoms of Na are in 0.300 moles of Na? • A: 0.0131 atoms • B: 7.86x1021 atoms • C: 1.81x1023 atoms • D: 6.02x1023 atoms

  32. Answer to Q#13 • Letter C: 1.81x1023 atoms • Why? 0.300 moles Na x 6.02x1023atom 1 mole = 1.81x1023 atoms

  33. Question #14 • How many moles are in a 342grams of CaO? • A: 6.10 moles • B: 56.1 moles • C: 1.92x104 moles • D: 3.67x1024 moles

  34. Answer to Q#14 • Letter A: 6.10 grams • Why? 342g x 1mole CaO = 6.10 moles 56.08 grams • 56.08 grams is the molar mass of CaO from the Periodic Table

  35. Moles Quick Review • When multiplying/dividing use lowest # of sig figs for answer • When adding/ subtracting use lowest # of decimal places for answer • MassMoles use mass of Periodic Table = 1 mole • Moles Particles use 1 mole = 6.02x1023 particles • Moles Liters at STP use 1 mole = 22.4 L

  36. Question #15 Be + 2HCl  BeCl2 + H2 • Using the above reaction, what mass of beryllium was consumed in the reaction if 4.0 moles of HCl were used? • A: 2.0grams • B: 9.0 grams • C: 18.0 grams • D: 36.0 grams

  37. Answer to Q#15 • Letter C: 18.0 grams • Why? • 4.0molsHCl x 1mols Be x 9.01gBe 2 mols HCl 1 mole Be = 18.0 grams Be

  38. Letter #16 2C2H6 + 7O2 4CO2 + 6H2O • In an experiment, 0.500 mols of C2H6 were reacted with 1.50 moles of oxygen gas. Which of the following is the limiting reactant in this experiment? • A: C2H6 • B: O2 • C: CO2 • D: H2O

  39. Answer to Q #16 • Letter B: O2 • Why? 0.500molsC2H6 x 4mols CO2 2 mols C2H6 = 1.00 mols CO2 • 1.50molsO2x4mols CO2 = 0.857molsCO2 7 mols O2 • Since O2 produces less CO2, it must be the limiting reactant • C and D shouldn’t even be choices b/c they are products!

  40. Stoich Quick Review • Mass A  Mols A Mols B  Mass B • Go from mols A  mols B using mol to mol ratio from coefficients of balanced equation • Limiting reactant is the one used up first. It also produces the smaller amount of product • % yield = (actual/theoretical) x100 • Can also use stoich to go from mass/mols of A to liters of B; use 22.4 L = 1mol at STP

  41. Question #17 • Which of the following is NOT a part of the kinetic molecular theory? • A: Gases move in a straight, continual motion • B: Gases have no volume themselves • C: Gases participate in inelastic collisions • D: Kinetic energy is directly related to temperature • E: Gases feel no attractive forces

  42. Answer to Q#17 • Letter C: Gases participate in inelastic collisions • Why? Gases actually participate in elastic collisions. • The other 4 parts are all TRUE

  43. Gas Laws Quiz Review • Boyle’s Law  P1V1 = P2V2, where P and V are inversely related. • Charles’ Law  V1/T1 = V2/T2 • Gay-Lusac  P1/T1 = P2/T2 • Combined Gas Law  (P1V1)/T1 = (P2V2)/T2 • Ideal Gas Law  PV = nRT, where R = 0.0821 (L*atm)/(mol*K)

  44. More Gas Laws Review • Must always convert temperature from celsius to KELVIN! • Absolute zero is -273C or 0K! • Absolute zero is the point where all motion slows down and stops • Dalton’s Law  P1+P2+P3… = Ptotal

  45. Question #18 • Which of the following phase changes occurs at the arrow? • A: Sublimation • B: Melting • C: Evaporation • D: Condensation

  46. Answer to Q#18 • Letter B: melting • Why? Graph always goes S, L, G—look at pic on right • The arrow points to line b/w solid and liquid • Only phase changes there are melting (SL) or freezing (LS)

  47. Phases Quick Review • 6 phases changes • Melting (SL) --Freezing (LS) • Evaporation (LG) --Condensation (GL) • Sublimation (SG) --Deposition (GS) • Molar heat of fusion = amount of energy needed to melt 1 mole of a substance • Molar heat of vaporization = amount of energy needed to evaporate 1 mole of a substance • Specific heat capacity = amount of energy needed to raise the temperature of 1 gram of a substance by 1˚C use q = mxCpxΔT

  48. IMF Quick Review • Four different intermolecular forces • London dispersion (weakest) = nonpolar covalent molecules • Dipole-dipole = polar molecules • Hydrogen bonding = H connected to N, O or F bonding to another O, N or F • Ionic (strongest) = metal + non-metal • Don’t forget to do the arrow test to determine polarity of a molecule

  49. Question #19 • How many moles of MgCl2 are present in 3.00 liters of a 0.150M MgCl2 solution? • A: 0.0500 moles • B: 0.450 moles • C: 1.35 moles • D: 20.0 moles

  50. Answer to Q#19 • Letter B: 0.450 moles • Why? Molarity (M) = mols/liters • So 0.150 M = x/3.00 L • (0.150M)(3.00L) = x • X = 0.450 moles

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