Regents Chemistry Exam August 2022
Tetrachloromethane, CCl4, was used as a dry cleaning solvent until it was banned for this use in the U.S. in 1970 due to its toxicity. This solvent was replaced in many dry cleaning processes by tetrachloroethene, C2Cl4. Another currently available alternative dry cleaning solvent is 1-bromopropane. The table below shows the boiling points of these solvents.
82 Explain, in terms of intermolecular forces, why tetrachloroethene has a higher boiling point than tetrachloromethane. [1]
Intermolecular forces are forces of attraction between molecules. The stronger the interomolecular forces are, the higher the boiling point is.
Answer: Tetrachloroethene has a higher boiling point than tetrachlomethane because it has stronger intermolecular forces.
83 Draw a structural formula for 1-bromopropane. [1]
If we take a look at Table P on the Reference table, we can see that prefix prop means there are 3 carbons. Ending "ane" means the molecule has all single bonds according to the Table Q. 1-bromo means there is a bromine attached to carbon 1. Finally, carbon wants to have 4 bonds.
The structure of 1-bromopropane is:
