what is the difference between enthalpy and entropy?

Question

thermodynamics

Answer 1

Entropy: The state of disorder in a thermodynamic system: the more energy the higher the entropy.

Enthalpy: The energy released or absorbed when a compound is formed from the elements in their standard states.

Entropy is the energy in the system, whereas enthalpy is the energy released or absorbed when a reaction takes place.

Answer 2

The Enthalpy of a reaction is the amount of energy the reaction requires to occur. The enthalpy is negative when the reaction releases heat, since the reaction does not require any energy; enthalpy is positive when the reaction needs energy to react. Enthalpy is determined by many things:
1) The number of bonds that needs to be broken and reformed
2) the stability of the reactants and products

A more complex explanation of enthalpy would be that it is the (energy needed to break all the bonds of the reactants) - (energy released from the forming of all the bonds of the products). It takes energy to break bonds, while forming bonds releases energy.

Entropy has a more complex definition. Entropy is commonly referred to as "the randomness" of the reactants or products. If there is a reaction: solid+ liquid <--> gas, then the randomness (entropy) of the reactants are low (because their molecules are very structured and ordered compared to the gas) and the randomness of the gas is high. Therefore, it would be harder for the gas to react, because each gas molecules would have to meticulously line up with the right steric factor (orientation and energy) in order to react, whereas the solids and liquids are already poised for reaction. This is why low entropy in the reactants will cause a faster forward reaction.

For further information, look up Gibb's Free Energy.

Answer 3

my daughter's bedroom is a good example of entropy - as each day passes it becomes more and more unorganised. Enthalpy is the amount of energy lost in there and equally the amount of energy i would have to expend to bring it back into order. In other words, everything in the universe will eventually decay and the energy that is used to maintain the chemical bonds that form the planets, stars, organisms etc will dissipate leaving only heat which will eventually slow down to nothing. To maintain these bonds requires heaps of energy - living organisms can maintain them for a short while using the sun as the primary energy source but eventually they die because the bonds give up. So imagine a teenagers bedroom and how much effort is required to keep it tidy and this is the universe and enthalpy and entropy in the microcosm!

Answer 4

enthalpy is the sum of the internal energy of a thermodynamic system plus the energy associated with work done by the system on the atmosphere;while entropy is the highest order of the disorder in the atmosphere leading to nucleus formation for a thermodynamic process to start.

Answer 5

The term Enthalpy is usually use to calculate the heat content of certain chemical reactions; such as enthalpy change of combustion,hydration etc...

hmm... I am not too sure about entropy though... but in simplicity, it's the measurement of how much energy is widely spreaded out in a chemical process.

Answer 6

Enthalpy deals with the energy within a system. Entropy deals with disorder and randomness.

Answer 7

enthalphy (it has an "h" in it for heat) refers to the heat content of a substance. Change in enthalpy refers to the quantity of heat transferred into our out of a system. Most systems try to achieve a state of lower energy.

entropy (it has an "r" in it for randomness) refers to the degree of randomness (disorder) in a system. Solids are usually very ordered (high entrophy), liquids less so and gases are the least ordered (least entrophy). Just remember that even a "disordered" system has order to it (ask any teenager to find something in their "disordered" room and they may know exactly where it is!). Most systems try to attain a state of maxiumum randomness.

Answer 8

check out www.dictionary.com