Concept explainers
Three processes that have been used for the industrial manufacture of acrylonitrile (CH2CHCN), an important chemical used in the manufacture of plastics, synthetic rubber, and fibers, are shown below. Use bond energy values (Table 3-3) to estimate ∆E for each of the reactions.
a.
b.
The nitrogen-oxygen bond energy in nitric oxide (NO) is 630. kJ/mol.
c.
(a)
Interpretation: The change in energy for the given chemical reactions has to be calculated.
Concept introduction: In a chemical reaction, energy is gained, endothermic reactions, or released, exothermic reactions. The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
To determine: The change in energy for the stated reactions.
Answer to Problem 152CP
The required energy change is
Explanation of Solution
Given
The chemical reaction involved is,
Figure 1
Formula
In the first reaction,
Figure 2
For first reactant,
Hence, the total energy required
For
Hence, the total energy required
Now, the total energy required for the reactants combined
Product bonds,
Hence,
The total energy released when the product is formed
So the change in energy for the first reaction is,
In the second reaction,
Figure 3
For the reactant,
Hence,
The total energy released when the product is formed
For product,
Hence,
The total energy released when the product is formed
For water,
So, the total energy of products
So the change in energy for the second reaction is,
The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
(b)
Interpretation: The change in energy for the given chemical reactions has to be calculated.
Concept introduction: In a chemical reaction, energy is gained, endothermic reactions, or released, exothermic reactions. The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
To determine: The change in energy for the stated reactions.
Answer to Problem 152CP
The required energy change is
Explanation of Solution
Given
The given reaction is,
Figure 4
For the reactant side,
For
The energy required
For
Total reactant energy
For products,
For
The total energy is
For
Since
For
The total energy for products is
So the change in energy for the second reaction is,
The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
(c)
Interpretation: The change in energy for the given chemical reactions has to be calculated.
Concept introduction: In a chemical reaction, energy is gained, endothermic reactions, or released, exothermic reactions. The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
To determine: The change in energy for the stated reactions.
Answer to Problem 152CP
The required energy change is
Explanation of Solution
Given
For the given reaction,
Figure 5
Energy for reactants,
For
Total energy
(since
For
Total energy
(since
For
The total energy of reactants
Energy for products,
For
The total energy
(since
For
Since
The total energy for products
So the change in energy for the second reaction is,
The change in energy can be stated as the difference between the energy required to break the bonds in case of reactants and the energy released on the formation of the products.
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Chapter 3 Solutions
Chemistry: An Atoms First Approach
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