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Chem Final Main concepts

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Quiz on Chem Final Main concepts, created by cheetahgoddess on 16/12/2014.
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Quiz by cheetahgoddess, updated more than 1 year ago
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Created by cheetahgoddess almost 10 years ago
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Resource summary

Question 1

Question
Select the correct description for O2 and O3. These two substances are:
Answer
  • elements, molecules, and isotopes
  • compounds, molecules, and isotopes
  • elements, molecules, and allotropes
  • compounds, molecules, and allotropes
  • molecules, allotropes, and isotopes

Question 2

Question
What key physical property was determined in Thomson's cathode ray experiment?
Answer
  • the charge of a proton
  • the mass-to-charge ratio of a proton
  • the mass of an electron
  • the mass-to-charge ratio of an electron
  • the spin of an electron

Question 3

Question
If an electron moves closer to a nucleus, which of the following is true regarding the electron energy and its chemical reactivity:
Answer
  • its energy increases and it become more reactive
  • its energy increases and it becomes less reactive
  • its energy decreases and it becomes more reactive
  • its energy decreases and it becomes less reactive

Question 4

Question
According to the Bohr model for a 1-electron atomic species ( where Z = atomic number, and n = principal quantum number) , the energy of the electron in the nth orbit is proportional to:
Answer
  • -Z^2 / n^2
  • -n / Z^2
  • -n / Z
  • -n^2 / Z^2
  • -Z^2 / n

Question 5

Question
Compared to the photon that would be emitted as a result of the n = 2 --> n = 1 electron transition in the hydrogen atom, would the photon emitted in the 2-->1 transition of the Li^2+ ion be of lower or higher energy?
Answer
  • lower
  • higher

Question 6

Question
Select the one process involving particle interactions that would result in a decreases in energy?
Answer
  • Two helium atoms move farther apart
  • A lithium ion moves farther away from a chloride ion
  • An electron moves from the n=1 level to the n = 2 level
  • an electron moves farther away from a nucleus
  • Two anions move farther apart

Question 7

Question
In diagrams of p orbitals, what is the significance of the difference colors or shadings given to the two lobes?
Image:
ss__2014-12-14_at_12.50.22_ (image/png)
Answer
  • Each lobe holds a different electron
  • The sign of the orbital wave function is positive in one lobe, negative in the other
  • The spin quantum number is +1/2 in one lobe, -1/2 in the other
  • The magnetic quantum number +1 in one lobe, -1 in the other
  • One lobe carried negative charge whereas the other lobe carries positive charge,

Question 8

Question
Which two quantum numbers are predictive of the energy of an electron in an orbital
Answer
  • ml and ms
  • n and ml
  • l and ml
  • l and ms
  • n and l

Question 9

Question
Which electron quantum number (QN) gives rises to the magnetic properties of atoms?
Answer
  • principal QN (n)
  • spin QN (ms)
  • angular momentum QN (l)
  • magnetic QN (ml)

Question 10

Question
Identify the main cause of the deceases in size as one moves across the row from left-to-right in the Periodic Table for relative atom sizes.
Answer
  • The atomic mass is increasing
  • The effective nuclear charge is increasing
  • Electron shielding is increasing
  • The number of electrons is increasing
  • The l quantum number is increasing

Question 11

Question
The following statements pertaining to electronegativity are all true except for one. Identify the one false statement.
Answer
  • Elements with lower energy valence orbitals have higher electronegativity
  • Metals are, in general, more electronegative than non mentals
  • Fluorine is the most electronegative element
  • Elements of high electronegativity are typically difficult to ionize
  • Electronegativity is a measure of how strongly an atom attracts bonding electrons

Question 12

Question
In general, how do non-metals compare to metals with regard to electronegativity and ionization energy? Non-metallic elements:
Answer
  • have higher electronegativities and are easier to ionize
  • have higher electronegativities and are more difficult to ionize
  • have lower electronegativities and are easier to ionize
  • have lower electronegativities and are more difficult to ionize

Question 13

Question
According to Valence Bond Theory, hybrid orbitals can be occupied by electrons that are found in:
Answer
  • pi bonds and lone pairs
  • sigma bonds only
  • sigma bonds, pi bonds, and lone pairs
  • sigma bonds and lone pairs
  • sigma bonds and pi bonds

Question 14

Question
All statements are true except for one. Identify the false statement.
Answer
  • pi bonds have no electron density on the internuclear axis
  • all covalent bonds contain one and only one sigma bond
  • when two atoms bond to form a diatomic molecule, the potential energy decreases
  • it is possible to form a sigma bond from two p atomic orbitals
  • pi bonds can be formed using ether s or p atomic orbitals

Question 15

Question
Graphite and diamond are two well-known allotropes of carbon. What is the hybridization of the carbon atom ins in each of these solids?
Answer
  • graphite - sp^3 diamond - sp^2
  • graphite - sp^2 diamond - sp
  • graphite - sp diamond - sp^3
  • graphite - sp^3 diamond - sp
  • graphite - sp^2 diamond - sp^3

Question 16

Question
The chemical composition of zeolites and clays is composed primarily of which three elements?
Answer
  • C, Fe, O
  • Si, Fe, O
  • Al, Ca, O
  • Al, Si, O
  • Mg, Si, O

Question 17

Question
For a specific substance, which one of the following process would result in the largest release of energy per mole?
Answer
  • evaporation
  • condensation
  • sublimation
  • melting
  • freezing

Question 18

Question
In the band theory for solid materials, Fermi level is the term that denotes the electron energy level corresponding to:
Answer
  • the highest occupied orbital
  • the lowest occupied orbital
  • the midpoint of the valence band
  • the midpoint of the conduction band

Question 19

Question
Which of the following conditions is always true for an extensive reaction? (CAUTION: carefully consider all choices before selecting an answer because certain conditions may be true for some reactions but not for all reactions.)
Answer
  • The value of ∆H° < 0
  • The value of ∆H° > 0
  • The value of ∆G° < 0
  • The value of ∆G° > 0
  • The value of ∆S° > 0

Question 20

Question
How does a catalyst affect the energetics of a reaction to increase the rate at which the reaction occurs?
Answer
  • by decreasing the free energy of the products
  • by decreasing the enthalpy of the products
  • by decreasing the activation energy
  • by increasing the collision frequency
  • by increasing the equilibrium constant

Question 21

Question
When a reaction attains equilibrium, identify the condition that must be satisfied. K s the equilibrium constant , and v is the reaction rate.
Answer
  • K = 0
  • K = 1
  • ∆G = 0
  • ∆G° = 0
  • v(forward) = v(reverse) = 0

Question 22

Question
If a chemical system consists of gas phrase molecules, which modes of motional freedom are available for dissipating heat transferred to the system from the surroundings?
Answer
  • rotational only
  • vibration only
  • rotation and translation
  • vibration and translation
  • translation, rotation, and vibration

Question 23

Question
Which of the following properties is not a thermodynamic state function?
Answer
  • heat
  • enthalpy
  • entropy
  • free energy
  • temperature

Question 24

Question
According to the Second Law of Thermodynamics, a reaction that occurs spontaneously will result in:
Answer
  • no change in the energy of the universe
  • a decrease in the energy of the system
  • an increase in the entropy of the universe
  • an increase in the entropy of the system
  • a decrease in the entropy of the universe

Question 25

Question
Of the following five factors, indicate all that can affect the rate of a reaction? Temperature, concentration of reactants, orientation of reactants at collision, activation energy, catalyst
Answer
  • temperature, concentration
  • temperature, activation energy
  • concentration, orientation, activation energy
  • activation energy, catalyst
  • all five of them

Question 26

Question
Hydrocarbons, for example, octane(C8H18), are insoluble in water, a phenomenon that is referred to as the hydrophobic effect. Thermodynamically, the standard free energy change for the reaction C8H18(l) <-> C8H18(aq) is extremely unfavorable (∆G° >> 0). Why does such a large increase in Gibbs free energy result when an octane molecule enters an aqueous phase?
Answer
  • the dispersion force interaction between water molecules and octane molecules is repulsive
  • a decrease in entropy occurs because water molecules around the octane molecule become more ordered ( with respect to bulk water)
  • a decrease in entropy occurs because water molecules around the octane molecule become more disordered ( with respect to bulk water)
  • an increase in enthaply occurs due to strong hydrogen bonding between octane molecules and water moelcules
  • an increase in enthaply occurs due to strong hydrogen bonding between octane molecules

Question 27

Question
Consider the three conceptual steps that we discussed for dissolving a molecular solid into a liquid solvent: (I) breaking intermolecular interactions that hold the solute molecules together in the solid (II) creating solvent cavities by breaking intermolecular interactions in the solvent (III) solute particles entering into the solvent cavities Which of these processes are endothermic?
Answer
  • I only
  • II only
  • III only
  • I and II
  • II and III

Question 28

Question
Identify the role of a reducatant ( reducing agent ) and the kind of valence orbital that gives rise to strong reductants?
Answer
  • electron acceptor; low energy unfilled valence orbitals
  • electron acceptor; high energy unfilled valence orbitals
  • electron donor; low energy occupied valence orbitals
  • electron donor; high energy occupied valence orbitals
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