Glossary
Adding Reactions (Keq)
Combining two or more individual chemical reactions to form an overall reaction, where the equilibrium constant for the overall reaction is the product of the individual Keq values.
Example:
To find the Keq for a multi-step process like A ⇌ B and B ⇌ C, you can determine the overall Keq by adding the reactions and multiplying their individual K values.
Enthalpy Change (ΔH)
The heat absorbed or released by a chemical reaction at constant pressure, representing the difference in enthalpy between products and reactants.
Example:
A negative ΔH value signifies an exothermic reaction, where heat is released into the surroundings, making the container feel warm.
Equilibrium Constant (Keq)
A value that expresses the ratio of product concentrations to reactant concentrations at equilibrium, indicating the extent to which a reaction proceeds towards products.
Example:
If the equilibrium constant for a reaction is very large, it means that at equilibrium, the reaction strongly favors the formation of products.
Flipping Reactions (Keq)
Reversing the direction of a chemical reaction, which causes the new equilibrium constant to be the inverse (1/K) of the original Keq.
Example:
If the Keq for A ⇌ B is 25, then after flipping the reaction to B ⇌ A, the new Keq will be 1/25 or 0.04.
Gibbs Free Energy (ΔG)
A thermodynamic quantity that measures the maximum reversible work that may be performed by a thermodynamic system at a constant temperature and pressure; it determines the spontaneity of a reaction.
Example:
A negative ΔG value indicates that a reaction is spontaneous under the given conditions, meaning it will proceed without continuous external energy input.
Haber Process
An industrial method for synthesizing ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂), vital for producing fertilizers and other chemicals.
Example:
Optimizing temperature and pressure conditions is crucial in the Haber Process to maximize the yield of ammonia, a key agricultural product.
Hess's Law
States that the total enthalpy change for a chemical reaction is the same, regardless of the number of steps or the path taken to achieve the overall reaction.
Example:
To find the overall enthalpy change for a complex reaction, you can use Hess's Law by summing the enthalpy changes of individual steps that add up to the net reaction.
Multiplying Reactions (Keq)
Scaling the stoichiometric coefficients of a chemical reaction by a factor 'n', which results in the new equilibrium constant being the original Keq raised to the power of 'n' (K^n).
Example:
If the Keq for X ⇌ Y is 4, then for 3X ⇌ 3Y, the new Keq after multiplying the reaction by 3 will be 4³, which is 64.
State Function
A property of a system whose value depends only on the current state of the system, not on the path taken to reach that state.
Example:
Temperature, pressure, and volume are all state functions because their values only depend on the current conditions, not how those conditions were achieved.