Chemistry Homework: Calculate Enthelpy Change

In summary, Enthalpy Change is a measure of the heat energy released or absorbed during a chemical reaction or physical process. It is calculated by subtracting the initial energy state from the final energy state of the system. Factors such as reactants, temperature, pressure, and catalysts can affect the value of Enthalpy Change. This concept has various real-life applications, including predicting the behavior of chemical reactions, understanding the energy requirements of living organisms, and assessing the impact of human activities on the environment. It can also be used to predict the feasibility of a reaction, with exothermic reactions being more likely to occur spontaneously compared to endothermic reactions. However, other factors such as entropy and activation energy must also be considered.
  • #1
shawonna23
146
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1. Calculate the approximate enthalpy change for the combustion of methane:
CH4 + 2O2 ---> 2H20 + CO2

2. Homework Equations

CH4 + 2O2 ---> 2H20 + CO2

enthalpy= D(reactants) - D(products)

D= bond dissociation energies

Bond Dissociation energy (KJ/MOL)

C-C 350
C=C 611
C-H 410
C-O 350
C=O 732
O-O 180
O=O 498
H-O 460

3. The Attempt at a Solution

ENTHALPY= D(reactants)-D(products)
[1640+(2*498)]-[(2*920)-1464]= -668 kJ
 
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  • #2
shawonna23 said:
[1640+(2*498)]-[(2*920)-1464]= -668 kJ

Why [(2*920)-1464]?

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FAQ: Chemistry Homework: Calculate Enthelpy Change

1. What is Enthalpy Change?

Enthalpy change is a measure of the heat energy released or absorbed during a chemical reaction or physical process. It is represented by the symbol ΔH and is typically measured in units of joules (J) or kilojoules (kJ).

2. How is Enthalpy Change calculated?

To calculate Enthalpy Change, you need to know the initial and final energy states of the system, as well as the amount of energy added or removed during the process. The formula for calculating Enthalpy Change is ΔH = Hfinal - Hinitial, where H represents the enthalpy of the system.

3. What factors can affect Enthalpy Change?

Enthalpy Change is affected by factors such as the nature and quantity of reactants, the temperature and pressure of the system, and the presence of a catalyst. Changes in these factors can alter the amount of energy released or absorbed during a reaction, thus affecting the value of Enthalpy Change.

4. What are some real-life applications of Enthalpy Change?

Enthalpy Change is an important concept in many fields, including chemistry, biology, and environmental science. It is used to understand and predict the behavior of chemical reactions, the energy requirements of living organisms, and the impact of human activities on the environment.

5. How can I use Enthalpy Change to predict the feasibility of a reaction?

The sign of Enthalpy Change (positive or negative) can indicate whether a reaction is exothermic (releases energy) or endothermic (absorbs energy). In general, exothermic reactions are more likely to be spontaneous and feasible, while endothermic reactions may require an input of energy to proceed. However, other factors such as entropy and activation energy also play a role in determining the feasibility of a reaction.

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