1.4.1 – Entropy
📌 What is entropy?
- Entropy is describes as a measure of disorder in the universe
- It is given by the symbol ‘S’
- Ordered states have low entropy, while disordered states have high entropy
- Entropy increases as energy becomes more dispersed
- Using this idea, we know that solids are the most ‘orderly’ and have the least energy dispersal while gases are the most ‘disorderly’ and have the greatest energy dispersal
- We can also predict that during state changes there is a change in entropy in the universe (eg. solid to liquid would increase entropy while gas to liquid would decrease it and so on)
- The absolute entropy of a substance can be calculated at STP and these values can be found in Section 13 of the data booklet
- The overall entropy change of a reaction can also be calculated using the formula below
Formula for calculating entropy change :
ΔS° = (∑S°products) – (∑S°reactants)