Without doing any calculations, determine the sign of ΔS_sys for each chemical reaction. a. 2 KClO₃(s) → 2 KCl(s) + 3 O₂(g) c. Na(s) + 2 Cl₂(g) → NaCl(s) d. N₂(g) + 3 H₂(g) → 2 NH₃(g)

Verified step by step guidance

1. <Identify the states of matter for each substance in the reaction.>
2. <Recognize that entropy (ΔS) is a measure of disorder or randomness in a system.>
3. <Note that gases generally have higher entropy than solids due to their greater freedom of movement.>
4. <Compare the number of moles of gaseous products to the number of moles of gaseous reactants.>
5. <Conclude that if the number of moles of gas increases, ΔS_sys is likely positive, indicating an increase in entropy.>

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 typically leads to an increase in entropy, while a decrease in the number of gas molecules can result in a decrease in entropy. Understanding how the states of matter and the number of particles change during a reaction is crucial for predicting the sign of ΔS.

States of Matter

The states of matter—solid, liquid, and gas—play a significant role in determining the entropy of a system. Solids have a fixed structure and lower entropy, while gases have more freedom of movement and higher entropy. In the given reaction, the transition from solid KClO3 to gaseous O2 indicates a change in the state of matter that affects the overall disorder of the system.

Chemical Reaction Stoichiometry

Chemical reaction stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. In the provided reaction, the stoichiometry shows that 2 moles of solid KClO3 produce 3 moles of gaseous O2 and 2 moles of solid KCl. This increase in the number of gaseous products relative to the reactants suggests an increase in entropy, which is essential for determining the sign of ΔS.