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Some more Regents Chemistry practice…

Some more Regents Chemistry practice…. What is the empirical formula of C 3 H 6 ?. A: CH. C: CH 3. B: CH 2. D: CH 6. Empirical formula is the simplified version of a molecular formula… C 3 H 6 – divide by greatest common factor (3) to get CH 2. B.

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Some more Regents Chemistry practice…

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  1. Some more Regents Chemistry practice…

  2. What is the empirical formula of C3H6? A: CH C: CH3 B: CH2 D: CH6

  3. Empirical formula is the simplified version of a molecular formula…C3H6 – divide by greatest common factor (3) to get CH2 B

  4. The name of the compound KClO2, is potassium A: chlorine oxide C: chlorate B: chlorite D: perchlorate

  5. ClO2– is a polyatomic ion since there is more than one capital letter…go to Table E and keep it as is B

  6. What is the percent by mass of carbon in HC2H3O2(gram-formula mass is 60)? A: 12 / 60 * 100 C: 24 / 60 * 100 B: 60 / 24 * 100 D: 60 / 12 * 100

  7. Table T:% comp by mass = part / whole * 100Since there are TWO carbon atoms…it is 24 / 60 * 100 C

  8. The measure of the attraction for electrons in a chemical bond is C: attractivity A: ionization energy B: atomic radius D: electronegativity

  9. Electronegativity…you can look up those values in Table S.Ionization energy is energy required to remove an electron. D

  10. Given the equation:H2 + Cl2→ 2 HClHow many moles of HCl will be produced when 3 moles of H2 is completely consumed? A: 3 moles C: 6 moles B: 2 moles D: 0.7 moles

  11. H2 + Cl2 → 2 HClSet up a ratio:eqn: 1 2 =?: 3 x C

  12. What type of bond exists between an atom of carbon and an atom of fluorine? A: ionic C: polar cov. B: metallic D: nonpolar cov.

  13. Has to be covalent because two nonmetals…Look up electronegativity values in Table S to see to that the difference is greater than 1.Polar: e- shared UNequallyNonpolar: e- shared equally C

  14. Which is held together by metallic bonds? A: NaCl C: CO B: Fe D: Br2

  15. Metallic bonding – look for the metal…Fe B

  16. The primary forces of attraction between water molecules in H2O are A: ionic C: molecule-ion B: hydrogen D: van der Waals

  17. Water molecules held together by hydrogen bonding…remember surface tension?floating a razor blade? B

  18. Which substance contains nonpolar covalent bonds? A: H2 C: Ca(OH)2 B: H2O D: CaO

  19. Covalent – must be two NONMETALSNonpolar – electrons shared equally…electronegativity difference less than 1. A

  20. What describes the electron dot structure of CaCl2? A: brackets without charges C: brackets with charges B: no brackets, no charges D: no brackets, but charges

  21. C CaCl2 is ionic (metal and nonmetal) so needs brackets AND charges… +2 -1 -1 [ ] [ ] [ ] Cl Ca Cl (gained 1 e-) (gained 1 e-) (lost 2 e-)

  22. Which statement best describes the following reaction?Cl + Cl → Cl2 + energy A: bond formed & energy released C: bond formed & energy absorbed B: bond broken & energy released D: bond broken & energy absorbed

  23. Two reactants become one product…bond is formedEnergy is on the product side…energy is released A

  24. The modern model of the atom shows that electrons are A: orbiting nucleus in fixed paths C: found in regions called orbitals B: combined with neutrons in the nucleus D: located in a solid sphere covering nucleus

  25. Modern model of atom = wave-mechanical model ORelectron cloud model…orbital = probable locations of e- C

  26. What is atomic number of an element that has 6 protons and 8 neutrons? A: 6 C: 8 B: 2 D: 14

  27. Atomic number = number of protons A

  28. What is the total number of protons contained in the nucleus of a carbon-14 atom? A: 6 C: 12 B: 8 D: 14

  29. The “14” in carbon-14 represents the mass number (protons + neutrons). If the atom is carbon…look up its atomic number. A

  30. Which of these elements has an atom with the most stable outer electron configuration? A: Ca C: Na B: Cl D: Ne

  31. Look for the noble gases in group 18…They have full valence shells. (2 e- for He, 8 e- for the rest) D

  32. What is the nuclear charge of an iron atom? A: +30 C: +56 B: +26 D: +82

  33. Protons and neutrons are in nucleus. Protons are positive and neutrons are neutral...making the charge on the nucleus positive. Look up atomic number of iron = 26. B

  34. How many electrons are in the outermost principal energy level of an atom of bromine in the ground state? A: 35 C: 2 B: 7 D: 8

  35. Look up the number of valence e-…Electron config: 2-8-18-7Valence e- are last number = 7…Group 17 has 7 valence e-. B

  36. Which electron configuration is correct for a sodium ion? A: 2-7 C: 2-8 B: 2-8-1 D: 2-8-2

  37. Na electron config as an ATOM is2-8-1It is in group 1 and will lose its 1 valence e- to become stable. C

  38. The nucleus of which atom contains 48 neutrons? 32 A: S 16 85 C: Rb 37 112 D: Cd 48 48 B: Ti 22

  39. Mass number is top number = protons + neutronsAtomic number is bottom number = number of protons(protons + neutrons) – (protons) = NEUTRONS C

  40. When an atom loses an electron, the atom becomes an ion that is A: (+) and larger C: (+) and smaller B: (-) and larger D: (-) and smaller

  41. Losing e-… (+) charge (look at oxidation state)When you lose weight, for example, you become smaller…the same goes for atoms & ions. C

  42. Spectral lines of elements are caused when electrons in an excited state move from A: low to high energy levels, absorbing energy C: low to high energy levels, releasing energy B: high to low energy levels, absorbing energy D: high to low energy levels, releasing energy

  43. An atom absorbs energy…electron jumps to higher energy level.(excited state)When the electron falls back to a lower energy level, energy is released in the form of light.(back to ground state) D

  44. What happens when NaCl is dissolved in water? A: Na+ ions attracted to O atoms of water C: Cl- ions attracted to O atoms of water B: Na+ ions are repelled by the O atoms of water D: Cl- ions are repelled by the H atoms of water

  45. Oxygen atoms have a partial negative charge so the Na+ ions are attracted to that side of the water molecule. A

  46. According to Table G, which solution at equilibrium contains 50 g of solute per 100 g of water at 75˚C? A: unsaturated solution of KCl C: unsaturated solution of KClO3 B: saturated solution of KCl D: saturated solution of KClO3

  47. Saturated solution is when falls right on the curve.Go over to 75 degrees and up to 50 g of solute. B

  48. Which compound is least soluble in 100 g of water at 40˚C? A: SO2 C: KClO3 B: NaCl D: NH4Cl

  49. When you go over to 40 degrees and then up…SO2 is the first solute you run into,which means it is the least soluble. A

  50. What is the total number of moles of solute in 2.0 L of 3.0 M NaOH? A: 6 moles C: 3 moles B: 2 moles D: 1 mole

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