Thermochemistry - Reaction between phosphorous and oxygen

In summary, Thermochemistry is the study of energy changes during chemical reactions and physical transformations. The reaction between phosphorous and oxygen results in the formation of phosphorus pentoxide and releases a large amount of heat energy. The enthalpy change for this reaction is -1640 kJ/mol, indicating a highly exothermic process. Temperature plays a crucial role in this reaction, affecting the rate of the reaction. Additionally, the reaction follows the law of conservation of energy, as the energy released is a result of the conversion of chemical energy to thermal energy.
  • #1
641
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i come across this fact.

red and white phosphorus are allotropes, but the reaction between white phosphorus with oxygen gives out slightly more heat than the reaction btw red phosphorus and oxygen.

P4 (s) [red] + 5O2 (g) --> 2P2O5 (s)

delta H = -30.2kJmol-1


P4 (s) [white]+ 5O2 (g) --> 2P2O5 (s)

delta H = -29.5kJmol-1

from the equation given, it show that the reaction btw red phosphorus and oxygen liberate more heat.


so, which one is correct?
 
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  • #2
Both. Ask yourself "What is the difference in enthalpies of formation of the allotropes?"
 
  • #3


Both equations are correct. The only difference between the two reactions is the allotrope of phosphorus used. Red phosphorus is more stable and less reactive than white phosphorus, which is why the reaction with oxygen releases slightly less heat. However, both reactions still release a significant amount of heat. The difference in enthalpy values could be due to experimental error or other factors such as the purity of the compounds used. Overall, both equations show that the reaction between phosphorus and oxygen is exothermic and releases energy in the form of heat.
 

What is Thermochemistry?

Thermochemistry is the study of the energy changes that occur during chemical reactions and physical transformations.

What happens during the reaction between phosphorous and oxygen?

In the reaction between phosphorous and oxygen, phosphorous combines with oxygen to form phosphorus pentoxide (P2O5). This reaction is highly exothermic, releasing a large amount of heat energy.

What is the enthalpy change for the reaction between phosphorous and oxygen?

The enthalpy change for the reaction between phosphorous and oxygen is -1640 kJ/mol. This indicates that the reaction is highly exothermic and releases a large amount of heat energy.

What is the role of temperature in the reaction between phosphorous and oxygen?

Temperature plays a crucial role in the reaction between phosphorous and oxygen. The reaction is highly exothermic, meaning that it releases a large amount of heat energy. Therefore, increasing the temperature will increase the rate of the reaction, while decreasing the temperature will decrease the rate of the reaction.

How does the reaction between phosphorous and oxygen relate to the law of conservation of energy?

The reaction between phosphorous and oxygen follows the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. In this reaction, the energy released in the form of heat is a result of the conversion of chemical energy into thermal energy.

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