Understanding Bond Enthalpies: Make and Break Bonds

In summary, bond enthalpy, also known as bond energy, is the amount of energy needed to break a chemical bond between two atoms in a molecule. This is typically measured using calorimetry, where the heat released or absorbed during a chemical reaction is measured. The strength of a bond enthalpy is influenced by factors such as the types of atoms involved, the distance between the atoms, and the presence of any neighboring atoms or functional groups. Understanding bond enthalpies is important for predicting the stability and reactivity of molecules, as well as designing and synthesizing new compounds with desired properties. Breaking a bond requires energy, while making a bond releases energy, and the net change in bond enthalpy is determined by the difference between
  • #1
Beeorz
30
0
Bond Enthalpies..please help!

Got the first one, but can't figure out how to do "b" and "c." Not understand which ones make/break.

http://rapidshare.com/files/157266091/Enth.jpg
 
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  • #2


If you don't see it, try brute force approach - list all bonds before reaction and after reaction.
 
  • #3


I would be happy to help you understand bond enthalpies and how to make and break bonds. First, let's review what bond enthalpy is. Bond enthalpy is the amount of energy required to break a chemical bond. It is also the amount of energy released when a bond is formed.

For part "b" and "c," it is important to understand which bonds are being made and broken. This can be determined by looking at the chemical equation or structure. For example, in the given image, we can see that in part "b," a carbon-carbon (C-C) bond is being broken and a carbon-hydrogen (C-H) bond is being formed.

To make a bond, energy must be released. This is because the atoms are coming closer together and forming a more stable bond. In contrast, breaking a bond requires energy to be absorbed. This is because the bond is being stretched and the atoms are moving farther apart, making the bond less stable.

To calculate the energy required to make or break a bond, we use bond enthalpy values. These values can be found in tables or databases and represent the average bond enthalpy for a particular type of bond. For example, the average bond enthalpy for a C-C bond is 348 kJ/mol, while the average bond enthalpy for a C-H bond is 413 kJ/mol.

To determine the total energy required to make or break a bond in a reaction, we can use a simple equation:

ΔH = Σ (bond enthalpy of bonds broken) - Σ (bond enthalpy of bonds formed)

In this equation, the Σ symbol represents the sum of all the bond enthalpies involved in the reaction. The bond enthalpies of the bonds being broken are subtracted because energy is being absorbed, while the bond enthalpies of the bonds being formed are added because energy is being released.

I hope this helps you understand bond enthalpies and how to make and break bonds. Remember to always pay attention to the type of bonds involved in a reaction and use bond enthalpy values to calculate the energy changes. If you have any further questions, please feel free to ask.
 

What is a bond enthalpy?

A bond enthalpy, also known as bond energy, is the amount of energy needed to break a chemical bond between two atoms in a molecule.

How are bond enthalpies measured?

Bond enthalpies are typically measured using a technique called calorimetry, where the heat released or absorbed during a chemical reaction is measured.

What factors affect bond enthalpies?

The strength of a bond enthalpy is influenced by several factors, including the types of atoms involved, the distance between the atoms, and the presence of any neighboring atoms or functional groups.

Why is understanding bond enthalpies important?

Understanding bond enthalpies is crucial in predicting the stability and reactivity of molecules. It also allows scientists to design and synthesize new compounds with specific properties.

How does breaking and making bonds affect bond enthalpies?

Breaking a bond requires energy, which is absorbed, while making a bond releases energy. The net change in bond enthalpy is determined by the difference between the energy absorbed and released in the process.

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