Question

Of the following reactions occurring at 25ºC, which one involves the greatest increase in entropy?H2(g) + Cl2(g) = 2 HCl(g)H2O(s) = H2O(l)Pb2+(aq) + 2 Cl-(aq) = PbCl2(s)CO2(s) = CO2(g)

Answer 1

Answer: [tex]CO_2(s)\rightarrow CO_2(g)[/tex]

Step-by-step explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

`\Delta S` is positive when randomness increases and
`\Delta S` is negative when randomness decreases.

a)
`H_2(g)+Cl_2(g)\rightarrow 2HCl(g)`

2 molesof gas are converting to 2 moles of another gas , thus
`\Delta S` is zero.

b)
`H_2O(s)\rightarrow H_2O(l)`

1 mole of solid is converting to 1 mole of liquid, the randomness increases and thus
`\Delta S` is positive.

b)
`Pb^(2+)(aq)+2Cl^-(aq)\rightarrow PbCl_2(s)`

2 moles of ions are converting to 1 mole of solid, the randomness decreases and thus
`\Delta S` is negative

d)
`CO_2(s)\rightarrow CO_2(g)`

1 mole of solid is converting to 1 mole of gas, the randomness increases drastically and thus
`\Delta S` is highly positive.