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Chapter 12 notes
ch 12 (chem 1)
17
Chemistry
Undergraduate 1
04/25/2010

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Term
What are the Strong IMF's?
Definition
high boiling point, high melting point, high ΔHvap, high ΔHfus, high ΔHsub, low VP
Term
What are the weak IMF's?
Definition
low boiling point, low melting point, low ΔHvap , low ΔHfus, low ΔHsub, high VP
Term
what is a dipole-dipole force?
Definition
a positive and a negative end of another molecule are attracted to each other
Term

which of the following molecules have dipole-dipole forces?

a) CO2

b) CH2Cl2

c) CH4

d) Cl4

e) CH3Cl

f) HCl

Definition

a) CO2               no

b) CH2Cl2          yes

c) CH4               no

d) Cl4                no

e) CH3Cl          yes

f) HCl                yes

Term
what is an ion-dipole force?
Definition
the attractive forces between an ion and a polar molecule
Term
Which should have more negative hydration energy, Cl- or Br-?
Definition
Br- is larger than Cl- so Cl- has the more negative ΔH hydration
Term
what is a London Dispersion force?
Definition
present in all molecules
Term

what type(s) of intermolecular forces exist between each of the following molecules?

a) HBr

b) CCl4

c) PF3

d) PCl5

e) SO2

f) CS2

g) H2S

Definition

a) HBr = dispersion forces, dipole-dipole forces

b) CCl4 = dispersion forces

c) PF3 = dispersion forces, dipole-dipole forces

d) PCl5 = dispersion forces

e) SO2 = dispersion forces, dipole-dipole forces

f) CS2 = dispersion forces

g) H2S = dispersion forces, dipole-dipole forces

Term
what is a hydrogen bod?
Definition
a dipole-dipole interaction between the hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O,N, or F atom
Term

Which of the following exhibits significant hydrogen bonding?

a) HBr

b) H2CF2

c) H2

d) CH3CN

e) CCl4

f) CH3CO2H

g) CH3COCH3

h) H2S

i) CH3CH2OH

Definition

a) HBr = no

b) H2CF2 = no

c) H2 = no

d) CH3CN = no

e) CCl4 = no

f) CH3CO2H = yes

g) CH3COCH3 = no

h) H2S = no

i) CH3CH2OH = yes

Term
what is vapor pressure?
Definition
the pressure of a vapor above a liquid at a given temperature
Term
what is vaporization?
Definition
the phase change from liquid to vapor
Term
what is condensation?
Definition
the phase change from vapor to liquid
Term
The molar enthalpy of vaporization of water is 40.7 kJ/mol at 100oC. How much energy is required to vaporize 925g of water at 100oC? (H2O = 18.02g/mol)
Definition

g --> mol --> kJ

925g x (1mol H2O/18.02g) x (40.7kJ/1mol H2O)

= 2.09 x 103kJ

Term
Calculate the mass of water that can be vaporized at its boiling point with 155kJ of heat. (ΔHvap = 40.7kJ/mol)
Definition

kJ --> mol --> g

155kJ x (1mol H2O/40.7kJ) x (18.02g/1mol)

= 68.6g H2O

Term
what is the Clausius-Clapeyron equation?
Definition

ln (P2/P1) = - (ΔHvap/R)(1/T2 - 1/T1)

 

R = gas constant (8.314 J/K mol)

Term

The vapor pressure of benzene C6H6, is 40.1mmHg at 7.6oC. What is the vapor pressure at 60.6oC?

(ΔHvap = 31.0kJ/mol)

Definition

ln (P2/P1) = - (ΔHvap/R)(1/T2 - 1/T1)

ln (P2/40.1mmHg) = - (31.0kJ/mol/8.314x10-3kJ/K mol)(1/333.6K - 1/218.6K)

ln (P2/40.1mmHg) = 2.11 (take the antilog of both sides)

P2/40.1mmHg = e2.11

P2 = e2.11 x 40.1mmHg

P2 = 331mmHg

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