Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the following polymers: (a) Lucite (Plexiglas); 59.9\% C, 8.06\% H, 32.0\% O (b) Saran; 24.8\% C, 2.0\% H, 73.1\% Cl (c) polyethylene; \(86 \%\) C \(, 14 \%\) H (d) polystyrene; \(92.3 \%\) C \(, 7.7 \% \mathrm{H}\) (e) Orlon; \(67.9 \%\) C, \(5.70 \%\) H, \(26.4 \%\) N

Polymer chemistry is a branch of chemistry that focuses on the synthesis, structure, and properties of polymers, which are large molecules made up of repeating subunits known as monomers. Due to the vast array of possible monomers and the ways they can combine, polymers can have diverse physical and chemical characteristics, making them suitable for a wide range of applications, from plastics and textiles to medicines and electronics.

Polymer chemists work to understand the relations between the structure and properties of polymers, which enables the design of new materials with specific qualities. A key aspect of polymer chemistry involves determining the empirical formula of a polymer, which provides a simplified representation of its composition without detailing the number of monomer units or the molecular weight of the actual polymer.

Molar mass is a fundamental concept in chemistry that refers to the mass of one mole of a substance, usually in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms within a molecular formula. For example, the molar mass of water (H₂O) is the sum of the molar masses of two hydrogen atoms (1.008 g/mol each) and one oxygen atom (16.00 g/mol), totaling approximately 18.02 g/mol.

This concept is essential in empirical formula calculations as it allows chemists to convert mass percentages to moles, which is necessary for determining the simplest whole number ratio of atoms in a compound. The molar mass of each element is used to calculate the moles of each element in a given mass of compound, serving as a bridge between the microscopic scale (atoms and molecules) and the macroscopic scale (grams).

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction. It's based on the conservation of mass and the concept of moles, allowing chemists to predict the amounts of substances consumed and produced in a reaction. Through stoichiometric calculations, we can determine the proportions in which chemicals react and form new products.

In the empirical formula calculation, stoichiometry is used to find the simplest integer ratio of moles of each element in the compound. This ratio helps to convert the elemental composition from moles to an empirical formula, which is a fundamental expression of a compound's proportional composition without regard to its actual quantity or molecular size. In essence, stoichiometry assists in bridging the gap between the mass of elements and their mole ratios necessary for empirical formula determination.

Chemical composition analysis involves identifying and quantifying the elements or compounds within a substance. Knowing the precise chemical composition is critical in various fields, including materials science, environmental studies, and pharmaceuticals. Methods of analysis can range from simple gravimetric techniques to sophisticated instrumental methods like mass spectrometry or nuclear magnetic resonance.

For determining empirical formulas, chemical composition analysis typically begins with the percentage by mass of each element in a compound. Assuming a hypothetical 100 grams of the substance simplifies the conversion of these percentages to grams. Using molar mass, those gram amounts are then transformed into moles, providing the necessary mole ratios to calculate the empirical formula. The empirical formula is the simplest whole-number representation of a compound's elemental composition and aids in understanding the basic architecture of a molecule.