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

검증된 단계별 안내

Identify the number of moles of gas molecules on both sides of the reaction. On the left side, there is one mole of CH₂=CH₂ and one mole of H₂, totaling two moles of gas. On the right side, there is one mole of CH₃CH₃.

Recognize that the entropy of a system, ΔS, is related to the number of ways particles can be arranged and the number of energy states they can occupy. More moles of gas generally mean higher entropy because there are more particles to arrange and more energy states available.

Compare the total moles of gas before and after the reaction. The reaction goes from two moles of gas on the reactants side to one mole of gas on the products side.

Conclude that the decrease in the number of gas moles leads to fewer available microstates for the system, thus reducing the system's entropy.

Determine the sign of ΔS_sys based on the change in entropy. Since the entropy decreases, ΔS_sys is negative.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

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.

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