1 thermodynamics : a measure of the unavailable energy in a closed thermodynamic system that is also usually considered to be a measure of the system’s disorder, that is a property of the system’s state, and that varies directly with any reversible change in heat in the system and inversely with the temperature of the

Gibbs or Boltzmann Factor • More generally the probability of a system being in a state of energy Ei and particle number Ni is given by the Gibbs factor

Entropy, the measure of a system’s thermal energy per unit temperature that is unavailable for doing useful work Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system

Entropy is simply a measure of disorder and affects all aspects of our daily lives In fact, you can think of it as nature’s tax Left unchecked disorder increases over time Energy disperses, and systems dissolve into chaos

In this page you can discover 17 synonyms, antonyms, idiomatic expressions, and related words for entropy, like: randomness, selective information, flux, kinetic-energy, information, potential-energy, wave-function, perturbation, solvation, angular-momentum and activation-energy

Entropy is basically the number of ways a system can be rearranged and have the same energy Chaos implies an exponential dependence on initial conditions Colloquially they can both mean “disorder” but in physics they have different meanings

Here’s the crucial thing about entropy: it always increases over time It is the natural tendency of things to lose order Left to its own devices, life will always become less structured Sand castles get washed away The Second Law of Thermodynamics states that the entropy of a closed system will never decrease

Entropy is a measure of the energy dispersal in the system We see evidence that the universe tends toward highest entropy many places in our lives A campfire is an example of entropy The solid wood burns and becomes ash, smoke and gases, all of which spread energy outwards more easily than the solid fuel

The second law states that there exists a useful state variable called entropy The change in entropy (delta S) is equal to the heat transfer (delta Q) divided by the temperature (T) The state of the gas would return to its original conditions and the change of entropy of the system would be zero

Temperature is the change in energy due to the change in entropy And since there is no negative sign, it is phrased as a positive — energy increases when entropy is added For a fixed temperature, if you double the entropy, the energy doubles also

Enthalpy, the sum of the internal energy and the product of the pressure and volume of a thermodynamic system In symbols, the enthalpy, H, equals the sum of the internal energy, E, and the product of the pressure, P, and volume, V, of the system: H = E + PV

4 Answers Standard definition: Enthalpy is a measurement of energy in a thermodynamic system It is the thermodynamic quantity equivalent to the internal energy of the system plus the product of pressure and volume

Enthalpy is the amount of internal energy contained in a compound whereas entropy is the amount of intrinsic disorder within the compound Enthalpy is zero for elemental compounds such hydrogen gas and oxygen gas; therefore, enthalpy is nonzero for water (regardless of phase)

Once you have m, the mass of your reactants, s, the specific heat of your product, and ∆T, the temperature change from your reaction, you are prepared to find the enthalpy of reaction Simply plug your values into the formula ∆H = m x s x ∆T and multiply to solve Your answer will be in the unit of energy Joules (J)

If ΔH is negative, the reaction is exothermic; if ΔH is positive, the reaction is endothermic Thermochemical equations have the general form: A+B→C,ΔH=(±n) A + B → C , Δ H = ( ± n )

Refrigerator compressors and chemical hand warmers are both real-life examples of enthalpy Both the vaporization of refrigerants in the compressor and the reaction to the iron oxidation in a hand warmer generate a change in heat content under constant pressure

An enthalpy diagram plots information about a chemical reaction such as the starting energy level, how much energy needs to be added to activate the reaction, and the ending energy An enthalpy diagram is graphed with the enthalpy on the y-axis and the time, or reaction progress, on the x-axis

A negative enthalpy represents an exothermic reaction, releasing heat A reaction that absorbs heat is endothermic Its enthalpy will be positive, and it will cool down its surroundings This reaction is exothermic (negative enthalpy, release of heat)

An energy diagram can be defined as a diagram showing the relative potential energies of reactants, transition states, and products as a reaction progresses with time The activation energy is the difference in the energy between the transition state and the reactants It’s depicted with a red arrow

Enthalpy changes Enthalpy change is the name given to the amount of heat evolved or absorbed in a reaction carried out at constant pressure It is given the symbol ΔH, read as “delta H”

When delta H is negative, it means the products in the reaction have lower energy compared to the reactants, so the reaction has lost energy and released it as heat, making it exothermic You can think of it as positive delta H as gaining energy and negative delta H as releasing energy

Q is the energy transfer due to thermal reactions such as heating water, cooking, etc anywhere where there is a heat transfer You can say that Q (Heat) is energy in transit Enthalpy (Delta H), on the other hand, is the state of the system, the total heat content

If H (enthalpy change) is zero, it means that the spontaneity of the reaction only depends on the entropy change (S) If entropy change for this reaction is +ve, the reaction will always be spontaneous at all temperatures If entropy change is -ve, the reaction will always be non-spontaneous at all temperatures

A negative enthalpy change represents an exothermic change where energy is released from the reaction, a positive enthalpy change represents an endothermic reaction where energy is taken in from the surroundings

3 What does it mean if Enthalpy is POSITIVE or NEGATIVE? A positive ∆H means that a reaction is endothermic as heat is absorbed from the surroundings to the system and the surroundings feel cold as the temperature decreases

The entropy of a substance increases (ΔS > 0) as it transforms from a relatively ordered solid, to a less-ordered liquid, and then to a still less-ordered gas The entropy decreases (ΔS < 0) as the substance transforms from a gas to a liquid and then to a solid