Thermochemistry
Key Idea 4: Work
How do scientists describe energy transfers as work?
In everyday language, the word work can have a variety of meanings. When someone asks, “What do you do for work?”, work refers to a person’s paid job. However, we also use the word work to mean directed effort on a difficult task; you may find studying chemistry to be hard work. However, in contrast to conversational use of this word, work has a very specific and precise scientific meaning.
What do we know?
Like heat, work is a means of transferring energy. Mathematically, work is a force that is exerted over a distance (F×d). If a system performs work on the surroundings, the internal energy of the system decreases. Alternatively, if work is performed on the system by the student workingsurroundings, the internal energy of the system increases.
This definition of work is very different from how the term work is used in everyday language. For instance, although studying chemistry may feel like very hard work, in scientific language, a person does not perform any work by reading or thinking. After all, no physical force is exerted when you study.