UNIT 1

Question 1

Unit Cell

Answer 1

smallest unit of a repeating Lattice

Question 2

Coordination number

Answer 2

Number of particles a cubic cell is in contact with

Question 3

Octahedral holes

Answer 3

Ions with a coordination number of 6

Question 4

Tetrahedral holes

Answer 4

Ions with a coordination number of 4

Question 5

Of the three cubic cells, which has the best packing efficiency?

Answer 5

Face Centered Cubic

Question 6

How many types of solids are there? what are the called?

Answer 6

4 types; Metallic, Ionic, Molecular, Covalent

Question 7

Describe the characteristics of Metallic Solids.

Answer 7

Composed of Metal atoms, metallic bonds, variable melting points, variable malleability and ductility, good conductivity.

Question 8

Describe the characteristics of Ionic Solids.

Answer 8

Composed of Cations and Anions, ion-ion bonds, High melting and boiling points, very hard, Solids are nonconductive and liquids are conductive.

Question 9

Describe the characteristics of Molecular Solids.

Answer 9

Composed of Molecules, contain dispersion, dipole-dipole, and H-bonding, Low melting/boiling points, Variable hardness; mostly soft, Nonconductive

Question 10

Describe the characteristics of Network Covalent Solids

Answer 10

Composed of a network of atoms, Covalent bonds (e- shared between 2 atoms), Very high melting points, very hard, nonconductive.

Question 11

What is Lattice Energy?

Answer 11

The energy of formation for a solid crystalline IONIC compound from component ions in the GAS phase.

Question 12

What is the equation for Lattice Energy that we can use to compare the LE between ionic compounds?

Answer 12

LE = q1q2/r
q = charge of each ion
r = distance between ions

Question 13

What is the relationship between charge and lattice energy? Between distance and lattice energy?

Answer 13

As charge (q) increases, lattice energy increases (proportional)

As distance (r) increases, lattice energy decreases (indirectly proportional)

Question 14

Which ionic compound has a higher Lattice Energy, NaCl or KBr?

Answer 14

NaCl would have the higher LE; While NaCl and KBr both have equal charge values, according to the atomic radius trend, NaCl is smaller than KBr. Because of this and the inverse relationship between size and LE, we can infer that NaCl will have a greater Lattice Energy than KBr.

Question 15

What is the relationship between lattice energy and the following: melting point, boiling point, ΔHvap/fus, and Vapor Pressure?

Answer 15

As Lattice Energy Increases, Melting point INCREASES

As Lattice Energy Increases, Boiling point INCREASES

As Lattice Energy Increases, ΔHvap/fus INCREASES

As Lattice Energy Increases, Vapor Pressure DECREASES

Question 16

What is vaporization? Is it endothermic/exothermic?

Answer 16

Vaporization - process by which molecules move from a liquid’s surface to form gas; vaporization is an Endothermic process (+)

Question 17

What is ΔHvap?

Answer 17

ΔHvap is the energy required to vaporize one mole of liquid at 1atm (typically in kJ/mol)

Question 18

What is Dynamic Equilibrium?

Answer 18

Rate of Condensation = Rate of Evaporation

Question 19

What is Vapor Pressure?

Answer 19

Vapor Pressure - pressure of vapor present at equilibrium; high VP = volatile (more likely to vaporize)

Question 20

What is the relationship between IMF strength and Vapor Pressure?

Answer 20

Higher IMF strength = Lower VP - strong IMFs make it harder for molecules to escape liquid state

Lower IMF strength = Higher VP - weak IMFs struggle to stop liquid molecules from escaping

Question 21

What is the relationship between temperature and Vapor Pressure?

Answer 21

As Temperature increases, Vapor pressure INCREASES

Inc Temp -> Higher KE -> easier to break IMFs -> easier for particles to escape liquid phase

Question 22

When does boiling point occur? What is “Normal Boiling Point?”

Answer 22

Boiling Point:
VP = atmospheric pressure

Normal Boiling Point:
VP = 1atm or 760mmHg/760torr

Question 23

What is the Clausius-Claperon Equation? What is it used to find? (Hint: Pressure Cooker!)

Answer 23

Equation: ln⟨P1∕P2⟩ = ΔHvap/R ·[1/T2 - 1/T1]

This equation is used to estimate VP at any temperature.

T = Kelvin
R = 0.008206

Question 24

What is a phase diagram?

Answer 24

A phase diagram tells us the state of a substance at a given temp and pressure.

Question 25

What are... A) Normal Melting Point B) Normal Boiling Point

Answer 25

A) temperature at which a solid melts at 1atm B) temperature at which a liquid boils at 1atm

Question 26

What is the Point of Sublimation?

Answer 26

The point of sublimation describes any temperature or pressure at which a solid changes to a gas.

Question 27

Describe the following: A) Critical Point B) Critical Temperature C) Critical Pressure D) Triple Point

Answer 27

A) Point under conditions in which no phase boundaries exist B) temperature above which vapor cannot be liquefied C) Pressure required to liquefy a gas at its critical temperature D) Conditions under which all three phases coexist in equilibrium

Question 28

What is the point of Rate Laws?

Answer 28

To describe the relationship between the rate of a chemical reaction and the concentration of the reactants.

Question 29

What is the formula for a rate law?

Answer 29

Rate = K[A]^n K = rate constant A = reactant n = reaction order - n = 0: zero order - n = 1: first order - n = 2: second order

Question 30

Characteristics of a zero-order reaction:

Answer 30

Rate = K[A]^0 = K[1] =K; constant rate Units = M/sec

Question 31

Characteristics of a first-order reaction:

Answer 31

Rate = K[A]^1; linear relationship - if [A] doubles, rate doubles Units = 1/sec

Question 32

Characteristics of a second-order reaction:

Answer 32

Rate = K[A]^2; exponential - if [A] doubles, rate quadruples Units = 1/M(sec)

Question 33

What are Integrated Rate Laws?

Answer 33

Provide the exact concentration of a reactant at any instantaneous time during a reaction (think calculus)

Question 34

What is a Reaction Half-Life?

Answer 34

The time it takes for the concentration of a reactant to be reduced to half of its original concentration.

Question 35

What is the equation for a zero-order Integrated Rate Equation? What factor(s) influence this order?

Answer 35

Eqn: [A] = -kt + [Ao] Slope = -k Half-life: [Ao]/2k Factor(s): Concentration

Question 36

What is the equation for a first-order integrated rate equation? What factor(s) influence this order?

Answer 36

Eqn: ln[A] = ln[Ao] - kt slope = -k Half-life: ln(2)/k Factor(s): independent of concentration

Question 37

What is the equation for a second-order integrated rate equation? What factor(s) influence this order?

Answer 37

Eqn: 1/[A] = 1/[Ao] + kt slope = +k Half-life: 1/k[Ao] Factor(s): dependent on concentration and INVERSELY proportional to initial concentration

Question 38

What is a rate limiting step? What does it do?

Answer 38

The rate limiting step is the slowest step in a reaction. This limits the overall rate and rate law for the reaction.

Question 39

What are Catalysts? What is Catalysis? A) homogeneous catalyst B) heterogeneous catalyst

Answer 39

Catalyst: A substance that increases the reaction rate without being consumed Catalysis: The ability of a species to increase the rate of a reaction A) a catalyst that is in the same phase as the reactants B) a catalyst that is in a different phase as the reactants

Question 40

When is a catalyst Included in the rate law equation?

Answer 40

When the catalyst is a reactant in the slow step (rate determining step)

Question 41

What is the Arrhenius equation and what is it used for?

Answer 41

Equation: ln(k2/k1) = Eq/R x (1/T1 -1/T2) This equation shows the relationship between reaction rate and temperature.