First Law of Thermodynamics

Definition

The First Law of Thermodynamics states that energy can be converted from one form to another, but it cannot be created or destroyed. It is the principle of conservation of energy, which says that the total energy of an isolated system is constant and energy can neither be created nor destroyed, but can only be transformed or transferred from one form to another.

5 Must Know Facts For Your Next Test

1. The First Law of Thermodynamics states that energy can be converted from one form to another, but it cannot be created or destroyed.
2. It is also known as the Law of Conservation of Energy, which means that the total energy of an isolated system is constant.
3. The First Law explains that energy can only be transformed or transferred from one form to another, not created or destroyed.
4. It is a fundamental principle in chemistry and physics, and is essential for understanding concepts like calorimetry and enthalpy.
5. The First Law is important in the context of energy changes in chemical reactions, where the total energy of the system remains constant.

Review Questions

• Explain how the First Law of Thermodynamics relates to the concept of calorimetry.
  • The First Law of Thermodynamics is crucial in the context of calorimetry, which is the measurement of the heat energy released or absorbed during a chemical reaction or physical process. According to the First Law, the energy released or absorbed in a calorimetric experiment is equal to the change in the internal energy of the system. This means that the heat absorbed or released by the system is directly related to the change in the system's internal energy, which can be measured and used to calculate the enthalpy change of the reaction.
• Describe how the First Law of Thermodynamics is connected to the concept of enthalpy.
  • The First Law of Thermodynamics is closely linked to the concept of enthalpy, which is the sum of a system's internal energy and the work done on or by the system due to changes in pressure and volume. The First Law states that energy can be converted from one form to another, but not created or destroyed. This principle is fundamental to understanding enthalpy changes in chemical reactions, where the total energy of the system (including the energy released or absorbed) remains constant, and the change in enthalpy reflects the energy transformation that occurs during the reaction.
• Analyze how the First Law of Thermodynamics can be used to predict the feasibility and direction of chemical reactions.
  • The First Law of Thermodynamics can be used to predict the feasibility and direction of chemical reactions by considering the changes in the system's internal energy and the work done on or by the system. If the change in the system's internal energy is negative (i.e., energy is released), the reaction is likely to be spontaneous and feasible. Conversely, if the change in internal energy is positive (i.e., energy is absorbed), the reaction may not be spontaneous and would require an input of energy to proceed. By analyzing the energy transformations described by the First Law, chemists can determine the thermodynamic favorability of a reaction and use this information to predict its feasibility and direction.

Related terms

Thermodynamics: The study of the relationship between heat, work, temperature, and energy.

Conservation of Energy: The principle that the total energy of an isolated system is constant and energy can neither be created nor destroyed, but can only be transformed or transferred from one form to another.

Energy Transformation: The process of changing energy from one form to another, such as converting electrical energy into heat energy.