In chemistry, the relationship between work (W) and internal energy (ΔU) is governed by the First Law of Thermodynamics. The First Law states that the change in internal energy of a system (ΔU) is equal to the heat transferred into the system (Q) minus the work done by the system (W). Mathematically, it can be expressed as:
ΔU = Q - W
This equation represents the conservation of energy principle in a chemical system. It states that the change in internal energy is the result of the energy transferred as heat (Q) and the work done on or by the system (W).
If work is done on the system (work done by the surroundings on the system), it is considered positive and increases the internal energy of the system. Examples of work done on the system include compression of gases, stirring or agitation, and mechanical work.
On the other hand, if work is done by the system (work done by the system on the surroundings), it is considered negative and decreases the internal energy of the system. Examples of work done by the system include expansion of gases against external pressure or doing mechanical work on the surroundings.
By considering the transfer of heat and work, the First Law of Thermodynamics provides a comprehensive understanding of the relationship between work and internal energy, allowing for the analysis and calculation of energy changes in chemical systems.
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