Interpretation:
The observations that carbon tetrachloride is liquid and ammonia is a gas at room temperature and pressure should be rationalized.
Concept Introduction:
Polar molecules have more boiling point due to partial ionic character between the ions. Net polarity is dependent on the structure of the molecule as, a molecule with atoms with electronegativity difference can be non-polar if all the dipole moments get cancelled out.
Carbon tetrachloride has a symmetrical tetrahedral structure in which the central carbon atom is attached to four chlorine atoms. Each bond has polarity, but the net polarity of the compound is cancelled due to the symmetrical structure of the compound. For this reason, carbon tetrachloride is a non-polar covalent compound.
Ammonia has a trigonal pyramidal structure in which the central nitrogen atom is attached to three hydrogen atoms. The molecule shows a net polarity, due to the polarity of each bond. For this reason, ammonia is a polar covalent compound.
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- Chemistry for Engineering StudentsChemistryISBN:9781337398909Author:Lawrence S. Brown, Tom HolmePublisher:Cengage Learning