Question

Which member of the following pairs would you expect to have a higher boiling point?

(a) N2 or F2, ?(b) SO2 or CO2,

(c) HF or HBr, ?(d) Ar or Xe,

(e) CO2 or CS2, ?(f) CCl4 or CH4,

(g) Cl2 or LiCl, ?(h) NH3 or PH3,

?(i) BH3 or NH3,?(j) F2 or I2?

Answer 1

SO2 and CO2

N2 >F2

Xe>Ar

F2 < I2

CCl4 > CH4

NH3 > PH3

HF < HBr]

CO2 <CS2

Answer 2

SO₂ or CO₂

SO₂ is nonlinear (trigonal planar electron cloud geometry) and so polar, and it also has a larger molecular mass than CO₂, which is linear and so nonpolar. Both of these factors favor SO₂ as having a higher boiling point

===========================================================================

HF or HBr,          HF molecules can hydrogen bond to one another, and so HF more likely has a higher boiling point than Hbr even though Hbr is larger and so has stronger dispersion forces

=-------------=========================================================

h) NH3 or PH3,

NH₃ is polar, and NH₃ molecules can hydrogen bond to one another

==============================================================

(a) N2 higher boiling

CCl4-----------higher boiling

HBr,----------higher boiling

higher boiling

higher boiling

Answer 3

(a) N2

(b) SO2

(c) HF

(d) Xe,

(e) CS2

(f) CCl4

(g) LiCl,

(h) NH3

           (i) NH3

        (j) I2