Final answer:
Polyethylene is a synthetic polymer with an empirical formula of CH₂, differing from oil, grease, and wax which are mixtures of hydrocarbons. Polyethylene's properties vary with chain length and branching, evidenced in HDPE, LDPE, and LLDPE forms. Combustion analysis helps determine the empirical formula of polymers like polystyrene.
Step-by-step explanation:
Differences between Polyethylene and Other Hydrocarbons
Polyethylene, oil, grease, and wax all contain the -CH2- unit in their structures; however, they differ significantly in physical properties and molecular structure. Polyethylene is a synthetic polymer formed from ethylene monomers (CH₂=CH₂) and is characterized by its long carbon chains. The empirical formula for polyethylene is CH₂. In contrast, oil, grease, and wax typically have a more complex composition with a mixture of hydrocarbons of varying chain lengths and are not polymers in the strict sense. Grease, for instance, is a semi-solid mixture containing oil and other thickening agents, while wax is composed of long-chain alkanes and esters.
Types of Polyethylene include High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), and Linear Low Density Polyethylene (LLDPE), which have different properties depending on chain length and degree of branching. As branching increases, the resulting polyethylene is softer with a lower melting point, such as LDPE. HDPE has a more linear structure, leading to a denser, stronger material.
In combustion analysis, polymers like polystyrene can be analyzed to determine their empirical formulae based on the mass of CO₂ and H₂O produced. The process involves burning a sample and measuring the resultant gases, allowing us to calculate the ratio of carbon to hydrogen atoms in the polymer.