CHEM 162 FINAL EXAM QUESTIONS
AND ANSWERS
Chemistry definition - Correct Answers -Study of structure, properties, transformations
of matter
Matter - Correct Answers -Anything that has mass + takes up space
Phases: solid, liquid, gas
Condensed phases = solids + liquids
Intermolecular Forces (IMF) - Correct Answers -= Interactions between
molecules/atoms/ions
Solution - Correct Answers -= Homogenous mixtures of 2+ pure substances
In a solution, the solute is dispersed uniformly throughout the solvent
- Solute = compound(s) in lesser amount
- Solvent = compound in greater amount
E.g. air
Ability of substances to form solutions depends on ... ? - Correct Answers -1) Natural
tendency toward mixing (always favorable):
- Entropy = measure of energy randomization/energy dispersal in a system
- All things in nature want to be as spread out/disordered as possible (AKA increase
their entropy)
- Solution formed = entropy of system is increased!
2) Intermolecular Forces (depends on solute-solvent interactions):
- Strength of IMF: attractive intermolecular forces are another one of the big driving
forces contributing to solution formation between solute/solvent molecules.
Covalent VS Ionic Compounds - Correct Answers -Covalent = generally more soluble in
nonpolar solvents, b/w 2 nonmetallic atoms
,Ionic = generally more soluble in polar solvents, b/w 2 atoms with opposite charge
Solute-Solvent interactions - Correct Answers -Soluble compound = can mix
homogeneously in all proportions with another compounds
Insoluble compound = cannot mix homogeneously in all proportions with another
compound
Miscible liquids = mix in all proportions with another liquid
Immiscible liquids = do not mix in one another
Range of solubility for all compounds: stronger the solute-solvent interaction, greater
solubility of a solute in that solvent
*** In order for a solute-solvent interaction to be favorable (soluble with each other),
both must have SIMILAR POLARITY! "LIKE DISSOLVES LIKE"
Solute-Solvent Combinations - Correct Answers -Soluble:
- Polar + polar: water, sugar
- Ionic + polar: "Hydration Shells" = solvent interface of any compound that consists of
the solute.
- Non-polar + non-polar: octane
Insoluble:
Non-polar + polar
Ionic + non-polar
Non-Polar Gases in Water - Correct Answers -London dispersion force = weakest IMF,
temporary attractive force when electrons in 2 adjacent atoms occupy positions that
make the atoms form temporary dipoles.
E.g. N2, O2, Ar, Kr in water
*** Larger gas = more soluble it will be in water
Solubility of non-polar gases is VERY low, but solubility will increase with increasing
London dispersion forces!
Solute-solute interactions (Forming a Solution) - Correct Answers -Must be
OVERCOME to DISPERSE PARTICLES when making a solution
These "interactions" could be IMF in covalent compounds, Coulombic attractions in
ionic compounds, metallic bonding in metals, etc.
Solvent-solvent interactions - Correct Answers -Must be OVERCOME to MAKE ROOM
for the solute (same types of interactions as above)
,Solvent-solute interactions - Correct Answers -Must be LARGE ENOUGH to
COMPENSATE FOR THE ENERGY that must be put into breaking solute-solute +
solvent-solvent interactions (same types of interactions as above)
Must be GREATER THAN solvent-solvent + solute-solute interactions to form solution,
because increasing entropy/creating more favorable IMF
= solvent-solvent + solute-solute interactions, solution still forms because entropy is still
increasing
solvent-solute < solvent-solvent, solute-solute: solution may or may not form, depending
on relative disparity (solution wants to form to increase entropy, but it may/may not
overcome breaking already-very-favorable interactions)
Relative energies of solution formation - Correct Answers -delta H (solution) = delta H
(solute) + delta H (solvent) + delta H (mixture)
delta H = heat energy "energy"
for a reaction to occur, delta H (mixture) must be close in magnitude to the sum of delta
H (solute) + delta H (solvent) - AKA solvent-solute >= solute-solute and solvent-solvent
*** Energetically favorable solution formation: decrease in enthalpy (thermodynamic
quantity) AND/OR increase in entropy (randomness)
Aqueous solution - Correct Answers -= Solution where the solvent is liquid water
Most common type
(Remember: solutions can be made with any phases of matter!)
Solubility of aqueous solutions - Correct Answers -Solubility = MAXIMUM amount of
solute that can dissolve in a given amount of solvent at a given temperature
Saturated solutions = have maximum amount of solute dissolved in the solvent to which
NO MORE SOLVENT can be dissolved at a given temperature
Unsaturated solutions = any amount of solute less than the maximum amount dissolved
in solution (at a given temperature).
Supersaturated solutions = have more solute dissolved than a saturated solution
(normally possible) at a certain temperature
Supersaturation - Correct Answers -Usually made by increasing the solvent's
temperature, making a saturated solution at the higher temperature, then cooling the
solution to a lower temperature very carefully
, These solutions are unstable - crystallization can usually be stimulated by adding a
"seed crystal" or scratching the side of the flask
Dissolving + Crystallization - Correct Answers -Dissolving = solutes into solvents
Crystallization = opposing process of dissolving, occurs when solute particles join back
together
Rate of opposing processes is equal = additional solute will not dissolve unless some
solute crystallizes from solution --> SATURATED SOLUTION
If we have not yet reached the amount that will result in crystallization -->
UNSATURATED SOLUTION
Temperature effect on solubility - Correct Answers -Generally, the solubility of SOLIDS
into liquids INCREASES with INCREASING TEMP
* Ce2(SO4)3 = exception
Examples:
- Making tea
- Making rock candy
Solubility of GASES into liquids DECREASES with INCREASING TEMP
Examples:
- Flattening of soda left out on a hot day
- Thermal pollution
Pressure effect on solubility - Correct Answers -Solubility of GASES into liquids
INCREASES with INCREASING PRESSURE
* Solubility of solids into liquids is not substantially effected by pressure!
Examples:
- Pop of soda when opening can
- Scuba diving accidents when coming up too fast
Why do bubbles form on the inside wall of a cooking pot when water is heated on the
stove, even though the water temperature is well below the boiling point of water? -
Correct Answers -Dissolved gases are less soluble in solution as temperature increases
Henry's Law - Correct Answers -= Quantifying the phenomenon that the solubility of
gases into liquids INCREASES with increasing pressure
AND ANSWERS
Chemistry definition - Correct Answers -Study of structure, properties, transformations
of matter
Matter - Correct Answers -Anything that has mass + takes up space
Phases: solid, liquid, gas
Condensed phases = solids + liquids
Intermolecular Forces (IMF) - Correct Answers -= Interactions between
molecules/atoms/ions
Solution - Correct Answers -= Homogenous mixtures of 2+ pure substances
In a solution, the solute is dispersed uniformly throughout the solvent
- Solute = compound(s) in lesser amount
- Solvent = compound in greater amount
E.g. air
Ability of substances to form solutions depends on ... ? - Correct Answers -1) Natural
tendency toward mixing (always favorable):
- Entropy = measure of energy randomization/energy dispersal in a system
- All things in nature want to be as spread out/disordered as possible (AKA increase
their entropy)
- Solution formed = entropy of system is increased!
2) Intermolecular Forces (depends on solute-solvent interactions):
- Strength of IMF: attractive intermolecular forces are another one of the big driving
forces contributing to solution formation between solute/solvent molecules.
Covalent VS Ionic Compounds - Correct Answers -Covalent = generally more soluble in
nonpolar solvents, b/w 2 nonmetallic atoms
,Ionic = generally more soluble in polar solvents, b/w 2 atoms with opposite charge
Solute-Solvent interactions - Correct Answers -Soluble compound = can mix
homogeneously in all proportions with another compounds
Insoluble compound = cannot mix homogeneously in all proportions with another
compound
Miscible liquids = mix in all proportions with another liquid
Immiscible liquids = do not mix in one another
Range of solubility for all compounds: stronger the solute-solvent interaction, greater
solubility of a solute in that solvent
*** In order for a solute-solvent interaction to be favorable (soluble with each other),
both must have SIMILAR POLARITY! "LIKE DISSOLVES LIKE"
Solute-Solvent Combinations - Correct Answers -Soluble:
- Polar + polar: water, sugar
- Ionic + polar: "Hydration Shells" = solvent interface of any compound that consists of
the solute.
- Non-polar + non-polar: octane
Insoluble:
Non-polar + polar
Ionic + non-polar
Non-Polar Gases in Water - Correct Answers -London dispersion force = weakest IMF,
temporary attractive force when electrons in 2 adjacent atoms occupy positions that
make the atoms form temporary dipoles.
E.g. N2, O2, Ar, Kr in water
*** Larger gas = more soluble it will be in water
Solubility of non-polar gases is VERY low, but solubility will increase with increasing
London dispersion forces!
Solute-solute interactions (Forming a Solution) - Correct Answers -Must be
OVERCOME to DISPERSE PARTICLES when making a solution
These "interactions" could be IMF in covalent compounds, Coulombic attractions in
ionic compounds, metallic bonding in metals, etc.
Solvent-solvent interactions - Correct Answers -Must be OVERCOME to MAKE ROOM
for the solute (same types of interactions as above)
,Solvent-solute interactions - Correct Answers -Must be LARGE ENOUGH to
COMPENSATE FOR THE ENERGY that must be put into breaking solute-solute +
solvent-solvent interactions (same types of interactions as above)
Must be GREATER THAN solvent-solvent + solute-solute interactions to form solution,
because increasing entropy/creating more favorable IMF
= solvent-solvent + solute-solute interactions, solution still forms because entropy is still
increasing
solvent-solute < solvent-solvent, solute-solute: solution may or may not form, depending
on relative disparity (solution wants to form to increase entropy, but it may/may not
overcome breaking already-very-favorable interactions)
Relative energies of solution formation - Correct Answers -delta H (solution) = delta H
(solute) + delta H (solvent) + delta H (mixture)
delta H = heat energy "energy"
for a reaction to occur, delta H (mixture) must be close in magnitude to the sum of delta
H (solute) + delta H (solvent) - AKA solvent-solute >= solute-solute and solvent-solvent
*** Energetically favorable solution formation: decrease in enthalpy (thermodynamic
quantity) AND/OR increase in entropy (randomness)
Aqueous solution - Correct Answers -= Solution where the solvent is liquid water
Most common type
(Remember: solutions can be made with any phases of matter!)
Solubility of aqueous solutions - Correct Answers -Solubility = MAXIMUM amount of
solute that can dissolve in a given amount of solvent at a given temperature
Saturated solutions = have maximum amount of solute dissolved in the solvent to which
NO MORE SOLVENT can be dissolved at a given temperature
Unsaturated solutions = any amount of solute less than the maximum amount dissolved
in solution (at a given temperature).
Supersaturated solutions = have more solute dissolved than a saturated solution
(normally possible) at a certain temperature
Supersaturation - Correct Answers -Usually made by increasing the solvent's
temperature, making a saturated solution at the higher temperature, then cooling the
solution to a lower temperature very carefully
, These solutions are unstable - crystallization can usually be stimulated by adding a
"seed crystal" or scratching the side of the flask
Dissolving + Crystallization - Correct Answers -Dissolving = solutes into solvents
Crystallization = opposing process of dissolving, occurs when solute particles join back
together
Rate of opposing processes is equal = additional solute will not dissolve unless some
solute crystallizes from solution --> SATURATED SOLUTION
If we have not yet reached the amount that will result in crystallization -->
UNSATURATED SOLUTION
Temperature effect on solubility - Correct Answers -Generally, the solubility of SOLIDS
into liquids INCREASES with INCREASING TEMP
* Ce2(SO4)3 = exception
Examples:
- Making tea
- Making rock candy
Solubility of GASES into liquids DECREASES with INCREASING TEMP
Examples:
- Flattening of soda left out on a hot day
- Thermal pollution
Pressure effect on solubility - Correct Answers -Solubility of GASES into liquids
INCREASES with INCREASING PRESSURE
* Solubility of solids into liquids is not substantially effected by pressure!
Examples:
- Pop of soda when opening can
- Scuba diving accidents when coming up too fast
Why do bubbles form on the inside wall of a cooking pot when water is heated on the
stove, even though the water temperature is well below the boiling point of water? -
Correct Answers -Dissolved gases are less soluble in solution as temperature increases
Henry's Law - Correct Answers -= Quantifying the phenomenon that the solubility of
gases into liquids INCREASES with increasing pressure
