Question

Reaction 1: NaCl(s) → Na+(aq) + Cl− Reaction 2: N2 + 3H2 → 2NH3 Which reaction leads to an increase in entropy?
Only Reaction 1
Only Reaction 2
Both Reaction 1 and 2
Neither Reaction 1 nor 2

Answer 1

Answer:

Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

combustion

combustion

Log burning in a fire. Burning wood is an example of a chemical reaction in which wood in the presence of heat and oxygen is transformed into carbon dioxide, water vapour, and ash.

Answer 2

Only Reaction 1 leads to an increase in entropy.

Entropy:

• Entropy is the amount of thermal energy per unit temperature in a system that is not available for meaningful work.
• Because work is obtained from organized molecular motion, entropy is also a measure of a system's molecular disorder or unpredictability.
• Entropy is both a scientific term and a measurable physical quality that is most usually linked with disorder, unpredictability, or uncertainty.

Factors affecting entropy:

• Change in Phase:

$S_{gas}$ >> $S_{liquid}$ > $S_{solid}$

• Because gaseous particles are very far apart and can move freely at high speeds, the entropy of a gas is significantly greater than that of a liquid.
• They do not need to be in close proximity to one another.
• Change in Temperature:
• As the temperature rises, the particles experience increased vibration (in solids) and faster movement (in liquids and gases).
• This leads to even more disarray. As a result, entropy rises.
• Change in Number of Particles:
• The number of moles of particles in a system produces more chaos and so increases entropy.
• Mixing of Particles:
• Mixing always results in an increase in disorderliness, i.e. an increase in entropy.

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