# Understanding Heat of Atomization: Equations and Problem-Solving Techniques

• Lori
In summary, the conversation discusses the confusion on how to write chemical equations for calculating the heat of atomization. The heat of atomization is defined as the heat needed to separate gaseous atoms from a substance in its standard state. The equations for the atomization of graphite and methane (CH4) were provided, along with the heat of formation for methane (-74.9 kj/mol) and the heat of atomization for methane (1660 kj/mol). The attempt at a solution included equations for the atomization of graphite and methane, but the equation for methane should only have CH4(g) on the left side. The last equation should also be doubled to account for the atomization of the entire methane molecule. The kj/mol values
Lori

## Homework Statement

So, my textbook doesn't go over these type of problems for heat of atomization , so I am confused on how to write the chemical equations for them.

Question: The heat of atomization is the heat needed to separated gaseous atoms from a substance in its standard state. The equation for the atomization of graphite is C(graphite) --> C(gas)

## Homework Equations

Given,
1) Heat of formation for CH4 = -74.9 Kj/mol
2)Heat of atomization for CH4 = 1660 kj/mol
3) heat of atomization for H2 = 423 kj/mol

## The Attempt at a Solution

For the equation number 1, i got C(graphite) + 2H2 -> CH4(s)
for number 2, i got C(graphite) + 4H -> C(g) + H(g)
For 3, i got 1/2H2(g) --> H(g)

I'm not sure if the second one is write. I was thinking that if i was able to write the equations correctly, then i can do some cancellation so i get C(graphite) --> C(gas).

CH4 is not solid (check your first equation). In the second you should have just CH4(g) on the left, not some combination of separated elements.

Borek said:
CH4 is not solid (check your first equation). In the second you should have just CH4(g) on the left, not some combination of separated elements.
Borek said:
CH4 is not solid (check your first equation). In the second you should have just CH4(g) on the left, not some combination of separated elements.
So it should look like this?

C(graphite) + 2H2(g) -> CH4(g)
CH4(g) -> C(g) + H(g)
1/2H2(g) --> H(g)

How would the kj/mol change for each equation? Would they remain the same?

First two equations look OK, I think the last one should be doubled - it is about atomizing a molecule, not half of the molecule. But in general you should check what definition you were given, as these things are often ambiguous.

## 1. What is the heat of atomization?

The heat of atomization is the amount of energy required to break apart one mole of a substance into its individual atoms in the gas phase.

## 2. Why is understanding heat of atomization important?

Understanding heat of atomization is important because it helps us understand the stability and reactivity of different molecules. It also allows us to calculate the amount of energy released or absorbed during chemical reactions.

## 3. How is the heat of atomization calculated?

The heat of atomization can be calculated using the enthalpy of formation and bond dissociation energies. The equation is: ΔH°atomization = Σ(ΔH°bond dissociation) + ΔH°formation

## 4. What are some common problem-solving techniques for heat of atomization?

Some common problem-solving techniques for heat of atomization include using Hess's Law, using bond enthalpies, and using standard enthalpies of formation. It is also important to pay attention to the phases of the substances involved in the reaction.

## 5. How does heat of atomization relate to other thermodynamic concepts?

Heat of atomization is closely related to other thermodynamic concepts such as enthalpy, entropy, and free energy. It is also related to bond energy, which is the amount of energy required to break a particular bond in a molecule.

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