Search results
Results from the WOW.Com Content Network
If the enthalpy changes are known for all the equations in the sequence, their sum will be the enthalpy change for the net equation. If the net enthalpy change is negative ( Δ H net < 0 {\displaystyle \Delta H_{\text{net}}<0} ), the reaction is exothermic and is more likely to be spontaneous ; positive Δ H values correspond to endothermic ...
Zwolinski and Wilhoit defined, in 1972, "gross" and "net" values for heats of combustion. In the gross definition the products are the most stable compounds, e.g. H 2 O (l), Br 2 (l), I 2 (s) and H 2 SO 4 (l). In the net definition the products are the gases produced when the compound is burned in an open flame, e.g. H 2 O (g), Br 2 (g), I 2 (g ...
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".
An enthalpy change describes the change in enthalpy observed in the constituents of a thermodynamic system when undergoing a transformation or chemical reaction. It is the difference between the enthalpy after the process has completed, i.e. the enthalpy of the products assuming that the reaction goes to completion, and the initial enthalpy of ...
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
Because the net variation in state properties during a thermodynamic cycle is zero, it forms a closed loop on a P-V diagram. A P-V diagram's abscissa, Y axis, shows pressure (P) and ordinate, X axis, shows volume (V). The area enclosed by the loop is the net work done by the processes, i.e. the cycle:
Δ r G, Gibbs free energy change per mole of reaction, Δ r G°, Gibbs free energy change per mole of reaction for unmixed reactants and products at standard conditions (i.e. 298 K, 100 kPa, 1 M of each reactant and product), R, gas constant, T, absolute temperature, ln, natural logarithm, Q r, reaction quotient (unitless),
Enthalpy is the transfer of energy in a reaction (for chemical reactions, it is in the form of heat) and is the change in enthalpy. Δ H {\displaystyle \Delta H} is a state function, meaning that Δ H {\displaystyle \Delta H} is independent of processes occurring between initial and final states.