Chem1 General Chemistry Virtual Textbook → Energetics → - - - - -

Some applications of enthalpy and the First Law

Chemical energetics: an introduction to thermodynamics

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- What you should be able to do
- Concept map

Virtually all chemical processes involve the absorption or release of heat, and thus changes in the internal energy of the system. In this section, we survey some of the more common chemistry-related applications of enthalpy and the First Law.

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What you should be able to do

Make sure you thoroughly understand the following essential ideas which have been presented above. It is especially imortant that you know the precise meanings of all the green-highlighted terms in the context of this topic.

- Describe the contrasting roles of thermodynamics and kinetics in understanding chemical change.
- Given a balanced net equation, write an expression for the rate of a reaction.
- Sketch a curve showing how the instantaneous rate of a reaction might change with time.
- Determine the order of a reaction of the form A → B + C from experimental data for the concentrations of its products at successive times.
- Describe the initial rate and isolation methods of determining the orders of the individual reactants in a reaction involving multiple reactants.
- Explain the difference between differential and integral rate laws.
- Sketch out a plot showing how the concentration of a component ([A] or ln [A]) that follows first-order kinetics will change with time. Indicate how the magnitude of the rate constant affects this plot
- Define the half-life of a reaction.
- Given the half-life for a first-order reaction A → products along with the initial value of [A]o, find [A]t at a subsequent time an integral number of half-lifes later.
- Describe the conditions under which a reaction can appear to have an order of zero.

Concept Map