chum

explain IMF boiling trend: F2, H2O, CBr4

• F2 = lowest BP b/c only has weak LDF

• H2O = H-bonding: much stronger IMF than F2 = higher BP than F2

• CBr4 = highest BP wo/ H-bonding b/c big E-cloud + high polarization = stronger LDF than H-bonds

• H2O forms H-bonds but smaller mcsize = total IMF < big disp in larger CBr mc

• BP trend increases w/ total IMF strength: weak disp in F2 < H-bond H2O < extreme disp from big MM CBr4

graph normal BP: propane

-45 C

graph normal BP: isobutane

-12 C

graph normal BP: butane

-0 C

explain IMF boiling trend: vapor/temp graph

• all 3 have LDFs + higher SA/more Es = stronger LDF

• butane mc = lots SA = more chances to make instantaneous dipoles

  • stronger LDF than propane/isobutane

highest VP: p/ib/b

propane

MC: H2O forward/reverse

C: sublimation & deposition

difference: evaporation VS boiling

• evaporation = on top of liquid, due to vapor/atmos P

• boiling = inside liquid, due to atmos P + heat/energy

circle change: endo VS exo

melting; endothermic

why vaporization heat > fusion heat

• more E to change state from liquid to gas than solid to liquid

• bc of big particle separation in gas state

MC: highest vaporization heat

CH3OH

calculate kJ to change 55g of ice at -18.5C to water 34C

• q = mcAt = 55⋅2.03⋅18.5 = 2,065.5 J

• q = mLf = 55⋅334 = 18,370J

• q = mcAt = 55 ⋅ 4.18 ⋅ 34 = 7,816.6 J

• qT = 2065.5+18370+7816.6 = 28252.1 J/1000 = 28.3kJ

2 NH3 mc’s in H-bonds picture

photo

2 H2Os in H-bonds + why BP: water > ammonia

H2O = 2 LPs on O mc / NH3 = only 1 LP

lets H2O mcs have more charges to bond w HB

MC: Br2 IMF

LDFs

MC: incorrect IMFs

lDf result

MC: mc has dipole-dipole forces

SCl2

mc: compounds w highest BP

CH3CH2CH2CH3 longest

mc: compounds w highest vapor P (2f)

CH3CH2CH2F

compound: lowest BP

CH4

T/F: stronger IMF = lowest VP

true

mc: SiO2, quartz (glass)

covalent network solid

mc: which’s discrete mc’s

CS2

what phase transition occurs btwn B/C

melting

allotrope meaning

element rearranged to form different substances w itself

allotropes of carbon examples

diamond, graphite, nanotubes

viscosity meaning + relation to IMFs

• measure of "internal friction" btwn molecules

  • stronger IMF = higher viscosity (slower flow)

  • weaker forces = lower viscosity (easier flow)