Employing the bond enthalpy values listed in Table 8.3 estimate the molar enthalpy change occurring upon c. formation of polyethylene terephthalate (PET).

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

Verified step by step guidance

Identify the chemical reaction involved in the formation of polyethylene terephthalate (PET). PET is formed through a condensation polymerization reaction between terephthalic acid and ethylene glycol.

Write the balanced chemical equation for the formation of PET. This will help in identifying the bonds broken and formed during the reaction.

List the bond enthalpy values for all the bonds involved in the reactants and products. You will need the bond enthalpies for C-H, C-C, C=O, O-H, and C-O bonds.

Calculate the total energy required to break all the bonds in the reactants. This involves multiplying the bond enthalpy of each bond by the number of such bonds broken and summing them up.

Calculate the total energy released in forming all the bonds in the products. Again, multiply the bond enthalpy of each bond by the number of such bonds formed and sum them up. The molar enthalpy change is the difference between the energy required to break the bonds and the energy released in forming the bonds.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bond Enthalpy

Bond enthalpy, or bond dissociation energy, is the amount of energy required to break one mole of a specific type of bond in a gaseous molecule. It is a crucial concept in thermochemistry as it helps predict the energy changes during chemical reactions. Higher bond enthalpy values indicate stronger bonds, which require more energy to break, influencing the overall enthalpy change of a reaction.

Molar Enthalpy Change

Molar enthalpy change refers to the change in enthalpy per mole of a substance during a chemical reaction. It is calculated by considering the bond enthalpies of the reactants and products. This concept is essential for estimating the energy changes associated with the formation or breaking of chemical bonds, allowing for the prediction of reaction feasibility and heat exchange.

Polyethylene Terephthalate (PET) Formation

Polyethylene terephthalate (PET) is a polymer formed through the condensation reaction of terephthalic acid and ethylene glycol. Understanding the formation of PET involves recognizing the types of bonds formed and broken during the reaction. The enthalpy change associated with its formation can be estimated using bond enthalpy values, which provide insight into the energy dynamics of polymerization processes.

Related Practice

Textbook Question

(a) What are the C—C—C bond angles in diamond?

583

views

Textbook Question

Although polyethylene can twist and turn in random ways, the most stable form is a linear one with the carbon backbone oriented as shown in the following figure:

The solid wedges in the figure indicate bonds from carbon that come out of the plane of the page; the dashed wedges indicate bonds that lie behind the plane of the page. (a) What is the hybridization of orbitals at each carbon atom? What angles do you expect between the bonds?

One method to synthesize ionic solids is by the heating of two reactants at high temperatures. Consider the reaction of FeO with TiO₂ to form FeTiO₃. Determine the amount of each of the two reactants to prepare 2.500 g FeTiO₃, assuming the reaction goes to completion. (b) Calculate the formula weight of FeTiO₃.

487

views

Textbook Question

Employing the bond enthalpy values listed in Table 8.4, estimate the molar enthalpy change occurring upon (a) polymerization of ethylene. (b) formation of nylon 6,6. (c) formation of polyethylene terephthalate (PET).

350

views

Textbook Question

(a) In polyvinyl chloride shown in Table 12.6, which bonds have the lowest average bond enthalpy?

2242

views