Lecture 16

Question 1

Tm= (Stands for)

Answer 1

Melting point

Question 2

Tb= (stands for)

Answer 2

Boiling point

Question 3

In order from weakest to strongest, attraction forces

Answer 3

Gas<Liquid<Solid (weakest<moderate<strongest)

Question 4

Phase changes- Melting
Include endo vs exo and delta H, and units of measure

Answer 4

Solid->Liquid (Endothermic), deltaH>0, Tm and -kJ/mol

Question 5

Phase changes-Condensation
Include endo vs. exo and delta H, and units of measure

Answer 5

Gas -> Liquid (exothermic), DeltaH<0

Question 6

Phase Changes-Sublimation
Include exo vs endo, deltaH, and units of measure

Answer 6

Solid-> Gas, (Endo OR exo -depends on the composition), Troom=22-25C/298.15K

Question 6

Phase changes-Evaporation
Include Exo vs Endo, delta H and volatile vs nonvolatile liquids

Answer 6

Liquid-> Gas (endothermic usually), delta H>0

Volatile = liquids evaporate quickly
non volatile = do not evaporate quickly

Question 7

Phase changes -Freezing
Include endo vs exo, delta H, and units of measure

Answer 7

Liquid-> Solid (Exothermic), deltaH<0, Tf (comp) ex: Tf(H20)=0C/273.26K

Question 8

Phase changes-Boiling
Include endo vs exo, delta H, and units of measure

Answer 8

Liquid-> Gas (endothermic), deltaH>0, Tb (H20 =100C/373.15K

Question 9

Surface tension definition

Answer 9

Liquids tend to minimize their surface *Resists penetration
*Stronger attraction =larger surface tension

Question 10

Surface tension equation

Answer 10

Surface Tension = Force (N) x Surface Area (m^2)

Question 11

Viscosity definition and qualities

Answer 11

Resistance of a liquids flow like oils.
Less round molecules shape =larger viscosity and also depends on number of carbons and Prescence of double bonds

Question 12

Vapor Pressure definition

Answer 12

The partial pressure exerted by the vapor

Question 13

Boiling point depends on

Answer 13

atmospheric pressure

Question 14

Vaporization units

Answer 14

Pvap deltaHvap=kJ/Mol and requires 40.7 kJ of heat to vaporize one mole of water @100C
deltaH condensation =-deltaH vaporization

Question 15

Hess’s Law

Answer 15

Enthalpy of a chemical process is independent of the path taken from the initial to the final state (i.e. enthalpy is a state function)

Or, DeltaH depends on HF (H formation) of reactants and products and doesn’t depend on the HF of the intermediate steps.

Question 16

Hess’s Law equation

Answer 16

DeltaH (RXN)=Sigma/kappa??HF (products)-Sigma/kappaHF(reactants)

Question 17

Enthalpy definition

Answer 17

Amount of heat (KJ/Mol, J/mol)

Question 18

Exothermic definition and unit

Answer 18

Heat released. DeltaH-RXN<0. Product is less than original reaction because heat is released.

P-R= T-#

Question 19

Endothermic reaction definition

Answer 19

Heat/energy absorbed. DeltaH-RXN >0. Product=More bc energy absorbed. P-R=T+#

Question 20

pound sign meaning in enthalpy equation

Answer 20

Activated complex

Question 21

Hf Simple units/equation

Answer 21

0kJ/Mol

Example: DeltaH RXN=2HF (CO) - [2 HF (C) +1 HF (O)= 2 x (-150.00)- [2.0 + 1.0] = -300.0 kJ/Mol (exothermic since - number)

Question 22

Stoichiometry of DeltaH RXN

Answer 22

G x Moles/Molarmass x kJ/Mol bc deltaH is measured in kJ/Mol