Predict in which of the following, entropy increases/decreases:(a) A l

1.	Predict in which of the following, entropy increases/decreases:(a) A liquid crystallize into a solid.(b) Temperature of crystalline solid is raised from 0 K to 115K.(c) 2NaHCO3 (s)→NaCO3(s)+CO2(g)+H2O(g).(d) H2(g)→ 2H(g).(e) A liquid changes into gas.
Answer» (a) When a liquid crystallizes into a solid, the molecules attain an ordered state and hence, entropy decreases. (b) At 0K, the constituent particles are static and entropy is minimum. If temperature is raised to 115K, these begin to move and oscillate about their equilibrium positions in the lattice and system becomes more disordered, hence entropy increases. (c) 2NaHCO₃(s) → Na₂CO₃(s) + CO₂ (g) + H₂O(g) In this reaction, the reactant, NaHCO₃ is a solid and it has low entropy. Among products, there are one solid and two gases. So, the products represent a condition of higher entropy. (d) H₂(g) → 2H(g) Here, one molecule of hydrogen gives two hydrogen atoms i.e. the number of particles increases leading to more disordered state. Two moles of H-atoms have higher entropy than one mole of dihydrogen molecule. (e) When a liquid changes into gas, the molecules attain a disordered state and so, entropy increases.

Predict in which of the following, entropy increases/decreases:(a) A liquid crystallize into a solid.(b) Temperature of crystalline solid is raised from 0 K to 115K.(c) 2NaHCO3 (s)→NaCO3(s)+CO2(g)+H2O(g).(d) H2(g)→ 2H(g).(e) A liquid changes into gas.

Answer»

(a) When a liquid crystallizes into a solid, the molecules attain an ordered state and hence, entropy decreases.

(b) At 0K, the constituent particles are static and entropy is minimum. If temperature is raised to 115K, these begin to move and oscillate about their equilibrium positions in the lattice and system becomes more disordered, hence entropy increases.

In this reaction, the reactant, NaHCO₃ is a solid and it has low entropy. Among products, there are one solid and two gases. So, the products represent a condition of higher entropy.

(d) H₂(g) → 2H(g)

Here, one molecule of hydrogen gives two hydrogen atoms i.e. the number of particles increases leading to more disordered state. Two moles of H-atoms have higher entropy than one mole of dihydrogen molecule.

(e) When a liquid changes into gas, the molecules attain a disordered state and so, entropy increases.

Predict in which of the following, entropy increases/decreases:(a) A liquid crystallize into a solid.(b) Temperature of crystalline solid is raised from 0 K to 115K.(c) 2NaHCO3 (s)→NaCO3(s)+CO2(g)+H2O(g).(d) H2(g)→ 2H(g).(e) A liquid changes into gas.

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