Easy ? Enthelpy Change. (Chem.)

In summary, combination reactions typically have a negative enthalpy, indicating that they are exothermic reactions. However, there are some exceptions such as dicyanoacetylene. Decomposition reactions usually have a positive enthalpy, indicating that they are endothermic reactions. When the enthalpy is negative, it means that energy is being released in the form of heat, while a positive enthalpy indicates that energy is required for the reaction to occur.
  • #1
Miike012
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Homework Statement





During a combination reaction such as..
P4(s) + 5O2(g) = P4O10(s) : DeltaH = -3010..

And for the decomposition reaction...

P4O10(s) = P4(s) + 5O2(g) DeltaH = 3010

Questions
1. Is it true that for any combination reaction that Enthalpy will be neg, and decomposition reactions that enthalpy will be positive?
2. when enthalpy is negative, this means that energy is being released? and when something requires energy, enthalpy will be pos?
 
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  • #2
I don't really know how to go about helping you without giving you the answer outright, but I will try.

If the enthalpy is negative, it is an exothermic reaction. So the real question is, "Are all combination reactions exothermic?", and "Are all Decomposition reactions endothermic?".

For the most part that is true, but there are some exceptions. Dicyanoacetylene, for example, has such a high endothermic formation heat, it can sometimes turn into carbon and nitrogen, which would be exothermic.

For question #2, the very definition of exothermic is that the reaction gives off heat. If the deltaH is negative, wouldn't that mean that energy is being released in the form of heat?
 

What is "Easy ? Enthelpy Change" in chemistry?

Easy ? Enthalpy Change, also known as ΔH, is a measure of the amount of heat energy that is absorbed or released during a chemical reaction at a constant pressure.

How is "Easy ? Enthelpy Change" related to the energy of a chemical reaction?

Easy ? Enthalpy Change is directly related to the energy of a chemical reaction. It represents the difference in energy between the products and the reactants of a chemical reaction, and can tell us whether the reaction is endothermic (absorbs heat) or exothermic (releases heat).

What factors can affect "Easy ? Enthelpy Change"?

Some factors that can affect Easy ? Enthalpy Change include the types of molecules involved in the reaction, the temperature and pressure at which the reaction occurs, and the physical state of the reactants and products (solid, liquid, or gas).

How is "Easy ? Enthelpy Change" measured?

Easy ? Enthalpy Change is typically measured using a calorimeter, which is a device that can measure the heat absorbed or released during a chemical reaction. The change in temperature of the reaction is used to calculate the Easy ? Enthalpy Change.

What is the significance of "Easy ? Enthelpy Change" in chemistry?

Easy ? Enthalpy Change is an important concept in chemistry as it helps us understand the energy changes that occur in chemical reactions. It can also be used to predict the direction and extent of a reaction, and to design and optimize industrial processes.

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