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Questions and Answers
Which factor primarily determines whether an ionic compound will dissolve in a polar solvent like water?
Which factor primarily determines whether an ionic compound will dissolve in a polar solvent like water?
- The strength of the covalent bonds within the ionic compound.
- The ratio of the cation's size to the anion's size.
- The number of electrons in the cation and anion.
- The relative strength of ion-dipole interactions compared to the lattice energy of the ionic compound and hydrogen bonding of water. (correct)
Why are nonpolar solvents generally ineffective at dissolving most ionic compounds?
Why are nonpolar solvents generally ineffective at dissolving most ionic compounds?
- Nonpolar solvents have very high dielectric constants.
- Nonpolar solvents are too viscous to allow ion movement.
- Nonpolar solvents do not effectively solvate separate ions due to a lack of strong intermolecular forces with the ions. (correct)
- Nonpolar solvents typically react with the ions, neutralizing their charges.
How does the polarity of a solvent affect the solubility of a molecular compound?
How does the polarity of a solvent affect the solubility of a molecular compound?
- Nonpolar solvents enhance the solubility of polar molecular compounds through dipole-induced dipole interactions.
- Polar solvents dissolve nonpolar molecular compounds due to London dispersion forces.
- Polar solvents tend to dissolve polar molecular compounds, and nonpolar solvents dissolve nonpolar molecular compounds, due to similar intermolecular forces. (correct)
- The polarity of a solvent has no impact on solvation of a molecular compound.
Which region of the electromagnetic spectrum is associated with vibrational transitions in molecules?
Which region of the electromagnetic spectrum is associated with vibrational transitions in molecules?
What type of molecular or electronic transition is typically associated with the absorption of ultraviolet (UV) light?
What type of molecular or electronic transition is typically associated with the absorption of ultraviolet (UV) light?
How is the energy of an emitted photon related to the electronic transition in an atom?
How is the energy of an emitted photon related to the electronic transition in an atom?
What happens to the wavelength of light emitted when an electron transitions from $n = 5$ to $n = 2$ compared to an electron transitioning from $n = 3$ to $n = 2$ in a hydrogen atom?
What happens to the wavelength of light emitted when an electron transitions from $n = 5$ to $n = 2$ compared to an electron transitioning from $n = 3$ to $n = 2$ in a hydrogen atom?
According to the Beer-Lambert Law, what is the relationship between the absorbance of a solution and the concentration of the absorbing species?
According to the Beer-Lambert Law, what is the relationship between the absorbance of a solution and the concentration of the absorbing species?
A solution has an absorbance of 1.0. If the path length is doubled and the concentration is halved, what will be the new absorbance, assuming the molar absorptivity remains constant?
A solution has an absorbance of 1.0. If the path length is doubled and the concentration is halved, what will be the new absorbance, assuming the molar absorptivity remains constant?
How does molar absorptivity ($\epsilon$) relate to the strength of a molecule's absorption of light at a particular wavelength?
How does molar absorptivity ($\epsilon$) relate to the strength of a molecule's absorption of light at a particular wavelength?
Flashcards
Solubility in Aqueous vs. Nonaqueous Solvents
Solubility in Aqueous vs. Nonaqueous Solvents
Ionic compounds dissolve well in polar solvents like water due to ion-dipole interactions. Molecular compounds' solubility depends on similar polarity; 'like dissolves like'.
EM Spectrum and Molecular Transitions
EM Spectrum and Molecular Transitions
Different regions of the electromagnetic spectrum (e.g., UV, IR, microwave) correspond to specific molecular transitions (electronic, vibrational, rotational).
Photon Energy and Electronic Transitions
Photon Energy and Electronic Transitions
The energy of an absorbed or emitted photon matches the energy difference between electronic energy levels in an atom or molecule.
Light Absorption and Concentration
Light Absorption and Concentration
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Study Notes
- Solubility depends on the intermolecular interactions between solute and solvent particles.
- "Like dissolves like" is a guiding principle.
- Polar solvents dissolve polar and ionic compounds due to favorable dipole-dipole or ion-dipole interactions.
- Nonpolar solvents dissolve nonpolar compounds through London dispersion forces.
- Aqueous solvents dissolve ionic compounds due to the strong ion-dipole interactions with water.
- Nonaqueous solvents are less effective at dissolving ionic compounds because they lack the strong interactions needed to overcome lattice energy.
Electromagnetic Spectrum and Molecular/Electronic Transitions
- Different regions of the electromagnetic spectrum correspond to specific types of molecular or electronic transitions.
- Radio waves induce nuclear spin transitions (NMR).
- Microwaves induce molecular rotational transitions.
- Infrared radiation induces vibrational transitions.
- Visible and ultraviolet light induce electronic transitions.
- Higher energy radiation (UV, X-rays) can cause ionization or bond breaking.
Photons and Electronic Transitions
- Absorption of a photon causes an electron to move to a higher energy level.
- Emission of a photon occurs when an electron transitions to a lower energy level.
- The energy of the absorbed or emitted photon is equal to the energy difference between the two electronic states involved in the transition (ΔE = hν).
- Each electronic transition has a specific wavelength and energy.
Light Absorption and the Beer-Lambert Law
- The amount of light absorbed by a solution is described by the Beer-Lambert Law: A = εbc.
- A represents absorbance
- ε represents molar absorptivity (a measure of how strongly a chemical species absorbs light at a given wavelength)
- b represents path length (the distance the light travels through the solution)
- c represents concentration of the solution
- Absorbance is directly proportional to the concentration of the solution and the path length of the light beam.
- Molar absorptivity is a constant for a given substance at a specific wavelength and indicates how strongly the substance absorbs light at that wavelength.
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