Enthalpy is the energy of the molecules. It cannot be measured, although CHANGE in enthalpy of reactions can be measured. It's simply heat energy. Exothermic reactions have anegative enthalpy change(which means energy of the products is lower than that of the reactants). Endothermic reactions have a positive value(energy of products is higher than that of the reactants). Entropy, on the other hand, is the degree of disorder. It's the measurement of how disordered a substance is. For example, particles in a solid are regularly arranged, so they are less disordered, and have a low value of entropy. Gases have much higher entropies. Entropy of an individual compound can be measured/calculated.
Enthalpy is the amount of energy in a system and when this changes (when a reaction happens), the energy is either released (exothermic) or absorbed (endothermic) and this energy is usually released or absorbed as heat. Therefore when the enthalpy decreases, heat is released from the system making it exothermic. In contrast, when the enthalpy increases, heat is absorbed making it endothermic.
Yes it is state function
Energy, Entropy and Efficiency........
The enthalpy of 17-4 PH stainless steel, like other materials, is not a fixed value and can vary depending on the temperature and phase of the material. Typically, the specific heat capacity for stainless steels is around 500 J/kg·K, which can be used in conjunction with temperature change to estimate enthalpy changes. For precise enthalpy values, reference to material property databases or specific experimental data is necessary.
Enthalpy mathematically is the sum of the internal energy and work done in a process.internal energy is the sum of the kinetic energy,potential energy,vibrational energies etc
No, ΔS (change in entropy) and ΔH (change in enthalpy) are not measurements of randomness. Entropy is a measure of the disorder or randomness in a system, while enthalpy is a measure of the heat energy of a system. The change in entropy and enthalpy can be related in chemical reactions to determine the overall spontaneity of the process.
Pressure is not affected by enthalpy and entropy.pressure
Temperature and energy are two of the variables included when graphing enthalpy and entropy. Enthalpy is made up of the energy, pressure, and volume of a system. Entropy is a way to determine the different ways energy can be arranged.
Enthalpy is the amount of energy released or used when kept at a constant pressure. Entropy refers to the unavailable energy within a system, which is also a measure of the problems within the system.
For delta G to become negative at a given enthalpy and entropy, the process must be spontaneous. This can happen when the increase in entropy is large enough to overcome the positive enthalpy, leading to a negative overall Gibbs free energy. This typically occurs at higher temperatures where entropy effects dominate.
In a chemical reaction, enthalpy, entropy, and free energy are related. Enthalpy is the heat energy exchanged during a reaction, entropy is the measure of disorder or randomness, and free energy is the energy available to do work. The relationship between these three factors is described by the Gibbs free energy equation: G H - TS, where G is the change in free energy, H is the change in enthalpy, S is the change in entropy, and T is the temperature in Kelvin. This equation shows that for a reaction to be spontaneous, the change in free energy must be negative, meaning that the enthalpy change and entropy change must work together in the right direction.
If the ∆H is positive and the ∆S is positive, then the reaction is entropy driven. If the ∆H is negative and the ∆S is negative, then the reaction is enthalpy driven. If ∆H is positive and ∆S is negative, then the reaction is driven by neither of these. If ∆H is negative and ∆S is positive, then the reaction is driven by both of these.
Changing the temperature
Gibbs energy accounts for both enthalpy (heat) and entropy (disorder) in a system. A reaction will be spontaneous if the Gibbs energy change is negative, which occurs when enthalpy is negative (exothermic) and/or entropy is positive (increased disorder). The relationship between Gibbs energy, enthalpy, and entropy is described by the equation ΔG = ΔH - TΔS, where T is temperature in Kelvin.
The relationship between enthalpy (H) and entropy (S) is described by the Gibbs free energy equation, ΔG = ΔH - TΔS, where ΔG is the change in Gibbs free energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. For a reaction to be spontaneous at higher temperatures but not at lower temperatures, the entropy term (TΔS) must dominate over the enthalpy term (ΔH) in the Gibbs free energy equation. This suggests that the increase in entropy with temperature plays a more significant role in driving the reaction towards spontaneity than the enthalpy change.
The units for entropy are joules per kelvin (J K-1)
The changes in enthalpy, entropy, and free energy are negative for the freezing of water since energy is released as heat during the process. At lower temperatures, the freezing of water is more spontaneous as the negative change in enthalpy dominates over the positive change in entropy, making the overall change in free energy negative and leading to a spontaneous process.