The total entropy change ΔStotal is the sum of the entropy changes of the system and of the surroundings. When an exothermic change takes place heat energy is transferred to the surroundings causing an increase in disorder to the surroundings. At higher temperatures, the molecules have a greater range of energies so they are more random and more disordered.Since ΔSθsurroundings = -ΔH / T (T is in kelvin) for all exothermic reactions ΔSθsurroundings is positive and for all endothermic reactions ΔSθsurroundings is negative.If the surroundings are hot, the entropy increase is small because the molecules are already in chaotic motion and already have a high entropy.
The Entropy Change of the Surroundings
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Specification: OCR Chemistry A (H432), A-level, 5.2.2 Enthalpy and entropy. Topic: Entropy.
Key terms in this lesson
- entropy
- A measure of the number of ways particles and their energy can be arranged, or the degree of disorder of a system.