Question

The binary hydrogen compounds of the group 4a elements and their boiling points are: ch4, -162°c; sih4, -112°c; geh4, -88°c; and snh4, -52°
c. explain the increase in boiling points from ch4 to snh4.

Answer 1

The polarity of the molecules determines the forces of attraction between the molecules in the liquid state. Polar molecules are attracted by the opposite charge effect (the positive end of one molecule is attracted to the negative end of another molecule. Molecules have different degrees of polarity as determined by the functional group present.

Principle: The greater the forces of attraction the higher the boiling point or the greater the polarity the higher the boiling point.

Answer 2

Explanation:

• All the molecules of the 4a elements are nonpolar and tetrahedral (AH4).
• The intermolecular forces found between these molecules are dispersion forces.
• The critical factor behind the strength of dispersion forces is the number of electrons.
• As the number of electrons increases, the strength of dispersion forces increases.
• So, the dispersion forces and the boiling points increases as the molar mass increases from CH4 to SnH4.