Understanding Enthalpy: Doubling Equations and Changes in kJ/mol

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In summary, when the equation 2Ch_4 \rightarrow 2C + 4H_2 \Delta H + 149.8 kJ is multiplied by 2, the change in enthalpy doubles. This is because the enthalpy change in the reduced form will always be the same, but in the second equation it is twice the amount due to the doubling of reactants and products.
  • #1
DB
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lets say u have:
[tex]Ch_4 \rightarrow C + 2H_2 \Delta H + 74.9 kJ[/tex]
When you multply the whole equation by 2, does the change in enthalpy double? or does it stay the same? keeping in mind that it's reduced to kJ/mol...
thanks
[tex]2Ch_4 \rightarrow 2C + 4H_2 \Delta H + 149.8 kJ[/tex]
??
 
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  • #2
yes, it would double
 
  • #3
sry my latex is messed up, the h should be capitalized and there should be a space in between the equation and the delta H

o so it would? how come? because I understand it as yes, when you double the amount of reactants and products you need double the energy, but even so, the enthalpy change in the equation in its reduced form, will always be the same...
 
  • #4
But the enthalpy change in the second equation is double because it _isn't_ in the reduced form - it's twice the amount. otherwise, I am not sure I am understanding your question.
 

FAQ: Understanding Enthalpy: Doubling Equations and Changes in kJ/mol

1. What is enthalpy?

Enthalpy is a measure of the total energy of a thermodynamic system. It is defined as the sum of the internal energy of the system plus the product of the pressure and volume of the system.

2. How is enthalpy related to energy?

Enthalpy is closely related to energy, as it is a measure of the total energy of a system. However, enthalpy also takes into account the pressure and volume of the system, making it a more useful measure in thermodynamics.

3. What is the difference between enthalpy and entropy?

Enthalpy and entropy are both measures of energy, but they represent different aspects of a system. Enthalpy is a measure of the total energy of a system, while entropy is a measure of the disorder or randomness of a system.

4. How is enthalpy used in chemistry?

Enthalpy is used in chemistry to measure the heat energy involved in a chemical reaction. It is often used to calculate the change in energy during a reaction, which is important in determining the feasibility and direction of a reaction.

5. What is the unit of measurement for enthalpy?

The unit of measurement for enthalpy is joules (J) in the International System of Units (SI). However, in some fields of science, such as chemistry and thermodynamics, the unit of kilojoules per mole (kJ/mol) is commonly used.

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