Question

Ratio of mass of repeating unit of Nylon-66 to repeating unit of nylon-6 is (A) 1 (B) 2 (C) 6 (D) 3

Short answer

The ratio of the mass of the repeating unit of Nylon-66 to the repeating unit of nylon-6 is 214:113, which does not match any of the provided options.

Step-by-step solution

Identify the repeating units of Nylon-66 and nylon-6

Nylon-66 is a copolymer formed from adipic acid (C6H10O4) and hexamethylene diamine (C6H16N2). The repeating unit of Nylon-66 can be written as [-CO-(CH2)4-CO-NH-(CH2)6-NH-]. Nylon-6 is a homopolymer formed from caprolactam (C6H11NO). The repeating unit of nylon-6 can be written as [-CO-(CH2)5-NH-].

Calculate the molecular mass of each repeating unit

First, we will calculate the molecular mass of the repeating unit of Nylon-66: Molecular mass of CO = 12 + 16 = 28 Molecular mass of (CH2)4 = (12 + 2 * 1) * 4 =44 Molecular mass of NH = 14 + 1 = 15 Molecular mass of (CH2)6 = (12 + 2 * 1) * 6 = 84 Thus, the molecular mass of the repeating unit of Nylon-66 = 28 + 44 + 28 + 15 + 84 + 15 = 214 Next, we will calculate the molecular mass of the repeating unit of nylon-6: Molecular mass of CO = 12 + 16 = 28 Molecular mass of (CH2)5 = (12 + 2 * 1) * 5 = 70 Molecular mass of NH = 14 + 1 = 15 Thus, the molecular mass of the repeating unit of nylon-6 = 28 + 70 + 15 = 113

Calculate the ratio of the masses of the repeating units

Now, we will find the ratio of the mass of the repeating unit of Nylon-66 to the mass of the repeating unit of nylon-6: Ratio = (Mass of repeating unit of Nylon-66) / (Mass of repeating unit of nylon-6) = 214/113

Simplify the ratio

Divide both 214 and 113 by the greatest common divisor (GCD) to simplify the ratio: GCD(214, 113) = 1 Ratio = 214/1 : 113/1 = 214:113 The ratio of the mass of the repeating unit of Nylon-66 to the repeating unit of nylon-6 is 214:113. Since none of the given options match this ratio, we can conclude that the correct answer is not provided in the given choices.

Key concepts

Repeating Units in Polymers

Polymers are large macromolecules composed of repeating structural units known as monomers. The specific arrangement and number of monomers in a chain dictate the properties of the polymer. In the case of nylons, which are a type of synthetic polymer, the difference between varieties such as Nylon-66 and nylon-6 lies in their respective repeating units.

Nylon-66 is formed from two different monomers, adipic acid and hexamethylene diamine, leading to a repeating unit with both acid and amine groups. In contrast, nylon-6 is generated from a single monomer, caprolactam, and has a simpler repeating structure. Understanding these fundamental units is crucial because they influence the polymer's melting point, durability, and how it interacts with other substances.

Calculating Molecular Mass

The molecular mass of a substance is the sum of the atomic masses of all atoms in a molecule. When calculating the molecular mass of repeating units in polymers, it is vital to accurately tally the mass contributions from each atom within the repeating structure.

To do so, identify each type of atom within the unit and multiply its atomic mass by the number of times it appears. Then, sum these values for all the different types of atoms to get the total molecular mass of the repeating unit. For example, in nylon-6, the molecular mass calculation includes contributions from carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).

Stoichiometry in Chemistry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships of reactants and products in a chemical reaction. In polymer chemistry, stoichiometry is applied to ensure that the right amounts of monomers react to form a desired polymer.

When creating polymers like Nylon-66 and nylon-6, the stoichiometric ratios of the starting materials must be precisely controlled to produce polymers with consistent properties. Moreover, stoichiometry is essential when comparing different polymers, as seen in the calculation of the molecular mass ratio, where the molecular formula of each repeating unit guides the comparison process.

Polymer Chemistry

Polymer chemistry is the study of the synthesis, structure, and properties of polymers. It's a field that blends concepts from organic chemistry, physical chemistry, and materials science to develop new materials with specific characteristics.

In the synthesis of polymers like nylons, the reaction conditions such as temperature, catalysts, and solvents can significantly affect the molecular structure and, as a result, the physical properties of the polymer. Both Nylon-66 and nylon-6 offer insights into polymer chemistry: Nylon-66 illustrates the formation of a copolymer, while nylon-6 represents homopolymers. Users of such materials should be aware that even subtle changes in composition and structure can lead to significant differences in performance.