Question

1. Out of the following, which system is decreasing in entropy? a. CH,OH,) → CH2OH() C. N2(g) + O2(g) → 2 NOG) b. NaClg) → Nataq) + Clian) d. 2 NO26) ► N20419 2. Which of the following is always spontaneous? a. C2H01) + 302(g) → 2CO2(g) + 3H2O(g) AH<0 b. Sublimation of solid CO2 C. Water freezing d. The formation of water from gaseous hydrogen and oxygen e. None of the above 3. Will liquid water evaporate at room temperature (25 °C) if the standard enthalpy of liquid water is -228.6 kJ.mol-1.K-1 and the standard enthalpy of water vapor is -237.1 kJ•mol:K. 4. When one mole of liquid water is frozen in a freezer at -10 °C, what are the relative values of ASsys and Assurr (which is bigger and are they positive or negative)? Is the reaction spontaneous?

Answer 1

1)
entropy of gas > entropy of aqueous > entropy of liquid > entropy of solid
This is because gas are more free to move around and hence there randomness is more.
Aqueous compound is mixture of solute and solvent and hence randomness is greater than solid form liquid.
In liquid molecules move more freely than solid. So, entropy of liquid is more than solid.

a)
Product has gas and reactant has liquid.
So, there is increase in entropy

b)
Product has aqueous and reactant has solid.
So, there is increase in entropy

c)
Both side we have 2 mol of gases.
So, entropy change is negligible

d)
On reactant there are 2 molecule of gases and in product there is only 1.
So, there is decrease in entropy

Answer: d

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