Chemistry 1100 Exam Review Flashcards

Chemistry 1100: Personal Performance Assessment #2 Notes

General Information

• Date: 3 October 2024

• Instructor: Professor Keller

• Format: Multiple choice and short answer.

• Important Constants:

  • 1 kg = 1000 g

  • 1 mol = 6.02 imes 10^{23} atoms

Multiple Choice Questions

Question 1: Absorption of Infrared Radiation by CO2

• When CO2 molecules absorb infrared radiation, the result is:

  • (D) they vibrate more.

Question 2: Atomic Masses in the Periodic Table

• The atomic masses are not exact integers because:

  • (C) Atomic masses listed in the periodic table are weighted averages of isotopic masses.

Question 3: Molecular Geometry

• The molecule with a tetrahedral molecular geometry is:

  • (D) CH2F2.

Question 4: CO2 Emissions and Atmospheric Accumulation

• Among the given answers, the best explanation for the difference in emissions is:

  • (B) The oceans have absorbed about one-third of the emitted CO2.

Question 5: The Octet Rule

• The octet rule means:

  • (E) each carbon atom forms bonds so as to have 8 electrons around it.

Question 6: Relationship between Ozone and Chlorine

• The relationship between stratospheric levels of atomic chlorine and ozone is:

  • (B) As chlorine increases, ozone decreases.

Question 7: Greenhouse Effect Representation

• Correct depiction of the greenhouse effect:

  • (A) (depiction not provided in the transcript).

Question 8: Carbon Cycle Processes

• The processes that add carbon to the atmosphere:

  • (C) I, II, and IV only (respiration, deforestation, combustion of fossil fuels).

Question 9: Breaking Chemical Bonds

• Breaking chemical bonds:

  • (A) costs energy.

Question 10: Atoms in One Mole of CH3OH

• The number of atoms in one mole of CH3OH is:

  • (A) 6.

Short Answer Questions

Question 11: Chloride Ions in Grain of Salt (NaCl)

• Weight of an average grain of salt: 6.48 imes 10^{-5} ext{ kg}.

• Number of chloride ions calculation:

  • 6.48 x 10^-5 kg = 6.48 imes 10^{-2} ext{ g} ext{ NaCl}

  • Convert grams to moles: rac{6.48 imes 10^{-2}}{58.4} ext{ mol} ext{ NaCl}

  • Number of chloride ions:

  • ext{moles NaCl} imes 6.02 imes 10^{23} ext{ ions/mol} = 6.68 imes 10^{20} ext{ ions}.

Question 12: Diimide (HNNH)

• (a) Lewis structure:

  • H-N=N-H

• (b) Molecular Structure:

  • H-N=N~H or N=N with alternating single and double bonds (specific representations not included).

• (c) Is diimide expected to be a greenhouse gas?

  • Yes. Explanation: It has vibrational modes due to its bonding structure.

Question 13: Jet Fuel Combustion

• Combustion reaction of jet fuel:

  • C{12}H{23} + 17 O2 ightarrow 12 CO2 + rac{23}{2} H_2O.

• Mass of CO2 released from burning 2.05 x 10^11 grams of jet fuel calculation:

  • 2.05 imes 10^{11} ext{ g } C{12}H{23} imes rac{1 ext{ mol } C{12}H{23}}{167.9 ext{ g}} imes rac{12 ext{ mol } CO2}{1 ext{ mol } C{12}H{23}} imes 44 ext{ g CO2} = 6.48 imes 10^{11} ext{ grams CO}_2.

Question 14: Steven Chu's Proposal on Climate Change

• Reasoning behind painting roofs white and using light-colored pavements:

  • Increases the albedo of the Earth's surface.

  • More incoming solar radiation is reflected rather than absorbed, leading to a cooling effect.

  • Energy savings can also occur as buildings remain cooler.

Question 15: Consequences of Global Warming/Climate Change

• Two potential consequences include:

  • Sea-level rise.

  • More extreme weather.

  • Ocean acidification, freshwater stresses.

Question 16: Reactions in the Stratosphere

• (a) Overall reactions:

  • Pair A: O_2
    ightarrow 2 O (Ozone depletion).

  • Pair B: O + O2 ightarrow O3 (Ozone formation).

• (b) Ozone formation corresponds to: Pair B.

• (c) Which UV photon has the shortest wavelength:

  • Circle: photon in Pair B.