Without doing any calculations, determine the sign of ΔSsys for each chemical reaction. b. CH₂=CH₂( g) + H₂( g) → CH₃CH₃( g)

Key Concepts

Entropy (ΔS)

Entropy, denoted as ΔS, is a measure of the disorder or randomness in a system. In chemical reactions, an increase in the number of gas molecules or a transition from a more ordered state to a less ordered state typically results in a positive ΔS, indicating greater disorder. Conversely, a decrease in the number of gas molecules or a transition to a more ordered state results in a negative ΔS.

Reaction Stoichiometry

Reaction stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. Understanding the stoichiometry helps in predicting changes in the number of molecules during a reaction. In the given reaction, analyzing the number of gaseous reactants and products is crucial for determining the sign of ΔSsys.

Phase and State Changes

The phase and state of matter play a significant role in entropy changes. Gaseous states generally have higher entropy than liquids or solids due to their greater freedom of movement. In the reaction provided, recognizing that all species are gases allows for a clearer assessment of how the reaction affects the overall disorder of the system.