Enthalpy

Definition

Enthalpy is a measure of the total energy of a thermodynamic system, including internal energy and the energy required to displace its environment. It is often used to quantify the heat change in biochemical reactions at constant pressure.

5 Must Know Facts For Your Next Test

1. Enthalpy changes are denoted by ΔH, which represents the difference between the enthalpy of products and reactants.
2. A negative ΔH indicates an exothermic reaction, releasing heat to the surroundings.
3. A positive ΔH signifies an endothermic reaction, absorbing heat from the surroundings.
4. In biological systems, enthalpy changes can influence metabolic pathways and enzyme activity.
5. The standard enthalpy change (ΔH°) is measured under standard conditions: 298K temperature, 1 atm pressure.

Review Questions

• What does a negative ΔH value indicate about a biochemical reaction?
• How does enthalpy relate to heat exchange in metabolic processes?
• Why is understanding enthalpy important for studying enzyme activity?

Related terms

Free Energy: The amount of work that can be extracted from a system at constant temperature and pressure.

Activation Energy: The minimum quantity of energy needed for a chemical reaction to occur.

Potential Energy:

Stored energy in an object or system due to its position or arrangement.