BForbes Chem II Final
A reaction that is not sponataneous at low temp can become spontaneous at high temps if delta H is ______________ and delta S is ___________.
+, +
For a reaction to be spontaneous under standard conditions at all temps, the signs of delta H and delta S must be ______________ and _____________, respectively.
-, +
In which of the following solutions will acetic acid have the greatest percent ionization?
0.01 M CH3COOH 0.1 M CH3COOH plus 0.1 M NH3
Which of the following is a buffer solution?
0.50 M NH4Cl and 0.10 NH3
Number of whole atoms in a simple cubic?
1
How do you MEASURE intermolecular forces?
1. Boiling Point 2. Melting Point 3. Hvap 4. Hfus 5. Hsub
Polarizability usually increases with...
1. Greater number of electrons 2. More diffuse electron cloud
What are at lattice points?
1. atoms 2. molecules 3. ions
What are 2 main properties of ice?
1. high specific heat - high boiling point 2. Ice is less dense than water
3 types of cubic cells?
1. simple cubic 2. body-centered cubic 3. face-centered cubic
What are the 7 types of unit cells?
1. simple cubic 2. tetragonal 3. orthorhombic 4. rhombohedral 5. monoclinic 6. triclinic 7. hexagonal
Number of whole atoms in a body-centered cubic?
2
What is the overall order of a reaction with the rate law: rate = k[NO]^2[02]?
3
Number of whole atoms in a face-centered cubic?
4
What are Ion-Dipole forces?
Attractive forces between an ion and a polar molecule.
What are dipole-dipole forces?
Attractive forces between polar molecules
What are dispersion forces?
Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules.
HB+ is a weak acid. Which chemical reaction below is governed by the equilibrium constant, Kb for B? (Pull base out and react w/ water.)
B (aq) + H20 (l) <-> HB+ + OH-
Change in S is positive for the reaction ________________.
BaF2 (s) ---> Ba2+ (aq) + 2F-
Why is H2 = 0 for Gibbs free energy?
Because H2 is in its natural state.
Delta H > 0 is an ______________ reaction.
Endothermic
Delta H < 0 is an ___________ reaction.
Exothermic
A catalyst is a substance that increases the rate of a chemical reaction while it is being consumed.
False
From the balanced chemical reaction for: 2A + B --> C + 2D, we can determine that its rate law is rate=k[A]^2[B].
False
Surface tension is defined as the resistance of a fluid to flow.
False
T/F. A covalent network solid is a crystalline solid with molecules at the lattice points.
False
T/F. A solution is a homogenous mixture of 2 or more substances.
False
T/F. At equilibrium the total concentration of reactants equals the total concentration of products, that is, [reactants]=[products].
False
T/F. Colligative properties are properties of solutions that depend on the number and nature of the solute particles.
False
T/F. Molality is a measure of solution concentration that is defined as the moles of solute dissolved per kilogram of solution.
False
T/F. The solubility of gases usually increases with increasing temperature.
False
T/F. The units of the equilibrium constant, Kc are M/s.
False
T/F. There is only one set of equilibrium concentrations that equals the Kc value.
False
When Qc>Kc, the reaction will shift towards the products to reach equilibrium.
False
The standard Gibbs free energy of formation of ___________ is zero.
H2 (g)
In the reacation NH3 + H20 <-> NH4 + OH-, the Bronsted acids are _____________.
H2O and NH4+
An aqueous phosphoric acid (H3PO4) solution contains the following species in varying concentrations: H3PO4, H2PO4-, HPO4^-2, PO4^-3, and H3O+ Which can act as both acids and bases?
H2PO4-, HPO4^-2
Which of the following acid is stronger? H2Se or H2S
H2Se
An aqueous phosphoric acid (H3PO4) solution contains the following species in varying concentrations: H3PO4, H2PO4-, HPO4^-2, PO4^-3, and H3O+ Which can only act as acids?
H3O+, H3PO4
Which of the following acid is stronger? H3PO3 or H2AsO3
H3PO3
Which of the following acid is stronger? HIO3 or HBrO3
HBrO3
Disperson forces usually _________ w/ molar mass.
Increase
Attractive forces between molecules.
Intermolecular forces
Hold atoms together in a molecule
Intramolecular forces
If detal G for a reaction is greater than zero, then __________________.
K<1
Which one of the following statements is true about the equilibrium constant for a reaction if delta G for the reaction is negative?
K>1
Identify which reactant is the Lewis acid and which is the Lewis base for the reaction: CH3-CH2-O- + CH3Cl <-> CH3-CH-O-CH3 + Cl-
Lewis Acid: CH3Cl Lewis Base: CH3-CH2-O-
Which of the following yields a basic solution when dissolved in water? a. NH4Cl b. P4O10 c. Li2O d. KNO3 e. CO2
Li2O
What are the strongest bases?
LiOH - lithium hydroxide NaOH - sodium hydroxide KOH - potassium hydroxide RbOH - rubidium hydroxide
What is the formula for molarity?
M = # of moles of solute/liters of solution
The higher the magnitude, the stronger the interaction. Which has a stronger interaction? Na+ or Mg2+?
Mg2+
Hydrogen bonds only occur with what elements?
N, O, F
Is a catalyst ever consumed during a reaction?
No
Which of the following would decrease the Ksp for Mg(OH)2?
None of the above - the Ksp of a compound is constant at constant temperature
An aqueous phosphoric acid (H3PO4) solution contains the following species in varying concentrations: H3PO4, H2PO4-, HPO4^-2, PO4^-3, and H3O+ Which can only act as bases?
PO4^-3
A homogeneous part of the system in contact with other parts of the system but separated from them by a well-defined boundary.
Phase
___________ is the energy required to expand the surface area of a liquid by a unit amount of area.
Surface tension
What is enthalpy?
Total energy
A unit cell is defined as the basic repeating unit of a crystalline solid.
True
According to Raoult's Law, the vapor pressure of a solvent over a solution increases as the mole fraction of the solvent increases.
True
Activation energy is the minimum energy needed to initiate a chemical reaction.
True
All molecules exhibit dispersion forces.
True
An increase in reaction rate that occurs when the concentrations of reactant molecules are increased results from an increase in the frequency of molecular collisions in the reaction vessel.
True
Hydrogen bonds can ONLY form between a hydrogen atom attached to a nitrogen, oxygen, or fluorine atom, and another nitrogen, oxygen, or fluorine atom.
True
In a system at equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.
True
Octane boils at 125 degrees C as compared to water, which boils at 100 degrees C. This info suggests that the dispersion forces in nonpolar octane molecules are stronger than dispersion forces and hydrogen bonding in water.
True
T/F. The molar heat of fusion of a substance is defined as the amount of heat required to melt one mole of the substance.
True
The units of "reaction rate" are M/s.
True
Intermolecular forces are much _________ than intramolecular forces.
Weaker
Which of the following characteristics indicates the presence of weak intermolecular forces?
a low boiling point
What is viscosity?
a measure of a fluid's resistance to flow
What intermolecular force(s) is (are) present in each of the following substances? a. ammonia (NH3) b. hydrogen chloride (HCl)
a. dispersion forces, hydrogen bonds b. dispersion forces, dipole-dipole
A Bronsted base is defined as a substance that ___________.
acts as a proton acceptor
Adhesion
an attraction between unlike molecules
Dissolving a solute such as sugar in a solvent such as water results in ________________________________.
an increase in the boiling point of the water
If delta G is = 0, that is ________________.
at equilibrium
In covalent crystals, lattice points are occupied by ______________.
atoms
Which of the following aqueous solutions has the highest boiling point? a. 0.2 m C6H12O6 (glucose) b. 0.2 m KCl c. 0.2 m Ca(NO3)2 d. a and b. e. Impossible to determine
c.
Which solution will have the highest pH? a. 0.10 M HCN b. 0.10 M HNO3 c. 0.10 M KOH d. 0.10 M NH3 e. 0.10 M H2CO3
c.
The triple point o iodine is at 0.12 atm and 115 degrees C. Thus, liquid iodine _________________________.
c. cannot have a vapor pressure less than 0.12 atm
What do superconductors do?
conduct electricity without any type of resistance
A saturated solution ____________________.
contains dissolved solute in equilibrium with undissolved solid
The entropy of the universe is ________________.
continually increasing
Which of the responses includes all of the following that can form hydrogen bonds with water molecules? (1) Na+ (2) CH3COOH (3) C2H6 (4) CH3NH2 a. (1) & (2) b. (1) & (3) c. (2) & (3) d. (2) & (4) e. (3) & (4)
d. (2) & (4)
What is an amorphous solid?
does not possess a well-defined arrangement and long-range molecular order.
Of the following, the entropy of ____________ is the largest. a. HCl (l) b. HCl (g) c. HCl (s) d. HBr (g) e. HI (g)
e
Of the following, the entropy of gaseous __________ is the largest at 25degC and 1 atm. a. CH4 b. C2H2 c. H2 d. C2H4 e. C2H6
e
Which of the following is always positive when a spontaneous process occurs? a. Change in Ssystem b. Change in Huniverse c. Change in Ssurroundings d. Change in Hsurroundings e. Change in Suniverse
e.
It's much ________ to evaporate water than to melt it.
easier
The disorder or randomness of a system is called _______________.
entropy
The thermodynamic quantity that expresses the degree of disorder in a system is _________.
entropy
The second law of thermodynamics states that _________________.
for any spontaneous process, the entropy of the universe increases
Which one of the following processes produces a decrease in the entropy of the system?
freezing water to form ice
The higher the Hvap, the ____________ the boiling point.
higher
In metallic crystals, lattice points are occupied by ______________.
metal atoms
In molecular crystals, lattice points are occupied by _____________.
molecules
The vaporization of PCl3 (l) is ___________.
nonspontaneous at low temps and spontaneous at high temps.
Which of the following is true with regard to a 0.001 M solution of a weak acid HA?
pH>3.0
What is a crystalline solid?
possesses rigid and long-range order. Predictable positions.
What are colligative properties?
properties of solutions that depend upon the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the type of chemical species present (NOT NATURE - IDENTITY)
If delta G is ever <0, it means that it's a __________ reaction.
spontaneous (exergonic)
If delta G is >), it means that it's a ___________ reaction.
spontaneous backwards (endergonic)
In liquids, the attractive intermolecular forces are ________________________________________.
strong enough to hold molecules relatively close together.
What is polarizability?
the ease with which the electron distribution in the atom or molecule can be distorted.
What is molar heat of vaporization?
the energy required to vaporize 1 mole of a liquid
Cohesion
the intermolecular attraction b/w like molecules
What is vapor pressure?
the pressure of a gas over its liquid phase
When a system is at equilibrium, _______________.
the process is not spontaneous in either direction
The pH at the equivalence point of a titration may differ from 7.0 due to ___________.
the reaction of the salt formed with water
With thermodynamics, one cannot determine ______________________.
the speed of a reaction
What is critical temperature?
the temperature above which the gas cannot be made to liquefy, no matter how great the applied pressure.
What is boiling point?
the temperature at which the equilibrium vapor pressure of a liquid is equal to the external pressure
Which of the following statements about the Kw is false?
the value of Kw is always 1.0 x 10^-14.
Kw= 1.0 x 10^-14 at 25degC. This indicates that _________.
water autoionizes only to a very small extent
A reaction that is spontaneous as written ____________.
will proceed without outside intervention
The pKa of a common indicator is equal to 4.7. Its un-ionized form (HA) is red and its anionic form (A-) is yellow. What color would this indicator solution have at pH = 6.8?
yellow
