AP Chemistry Unit 2 Corrections

Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl? A) NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF B) NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl C) NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF D) NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than in MgO

A) NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF NaCl has a weaker coulombic attraction than NaF because chlorine has a larger atomic radius; a weaker coulombic attraction signify that bonds are weak, so boiling point is low.

Which of the following lists Mg, P, and Cl in order of increasing atomic radius? A) Mg < Cl < P B) P < Cl < Mg C) Cl < P < Mg D) Cl < Mg < P E) Mg < P < Cl

C) Cl < P < Mg Atomic radius increases going down a group and decreasing going across a period; according to this trend, chlorine's size is smaller than phosphorus, which is smaller than magnesium.

If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO2? A) Benzene C6H6 B) Cyclohexane C6H12 C) Glucose, C6H12O6 D) Methane, CH4

A) Benzene C6H6 The molecule with the greatest amount of carbon will yield the greatest mass of CO2. C6 = 72 H6 = 6 72 + 6 = 78 72/78 x 100 = 92%

The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum (N) being to the right of the peak on the lower spectrum (O). A) Nitrogen atoms have a smaller nuclear charge than oxygen atoms B) Electrons in the p subshell of oxygen atoms provide more shielding than the electrons in the p subshell of nitrogen atoms C) Nitrogen atoms have a half-filled p subshell D) There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms

A) Nitrogen atoms have a smaller nuclear charge than oxygen atoms. Nitrogen's nuclear charge is 7, which is smaller than oxygen's (8). Since oxygen is closer to an octet, it takes more energy to remove the first electron.

Which of the following correctly identifies which has the higher first-ionization energy, Cl or Ar, and supplies the best justification? A) Ar, because of its completely filled valence shell B) Ar, because of its higher effective nuclear charge C) Cl, because of its higher electronegativity D) Cl, because of its higher electron affinity

B) Ar, because of its higher effective nuclear charge. Argon's nuclear charge is 8+, which is higher than chlorine's (7+); as nuclear charge increases, first-ionization energy increases; it's a direct relationship.