Answer: Molecules of gas are usually far apart and can be compressed unlike molecules of liquids.
Explanation:
The molecules of gases are usually far apart, moving freely and randomly, occupying extra space in the containing vessel. Hence, when compressed to become closely packed, gases have lower volume.
However, unlike gases, the molecules of a liquid are restricted, move less freely and occupy no extra space. Hence, liquids cannot be compressed, and their volume remains the same in their containing vessel.
Answer:
(a) ΔSº = 216.10 J/K
(b) ΔSº = - 56.4 J/K
(c) ΔSº = 273.8 J/K
Explanation:
We know the standard entropy change for a given reaction is given by the sum of the entropies of the products minus the entropies of reactants.
First we need to find in an appropiate reference table the standard molar entropies entropies, and then do the calculations.
(a) C2H5OH(l) + 3 O2(g) ⇒ 2 CO2(g) + 3 H2O(g)
Sº 159.9 205.2 213.8 188.8
(J/Kmol)
ΔSº = [ 2(213.8) + 3(188.8) ] - [ 159.9 + 3(205.) ] J/K
ΔSº = 216.10 J/K
(b) CS2(l) + 3 O2(g) ⇒ CO2(g) + 2 SO2(g)
Sº 151.0 205.2 213.8 248.2
(J/Kmol)
ΔSº = [ 213.8 + 2(248.2) ] - [ 151.0 + 3(205.2) ] J/K = - 56.4 J/K
(c) 2 C6H6(l) + 15 O2(g) 12 CO2(g) + 6 H2O(g)
Sº 173.3 205.2 213.8 188.8
(J/Kmol)
ΔSº = [ 12(213.8) + 6(188.8) ] - [ 2(173.3) + 15( 205.2) ] = 273.8 J/K
Whenever possible we should always verify if our answer makes sense. Note that the signs for the entropy change agree with the change in mol gas. For example in reaction (b) we are going from 4 total mol gas reactants to 3, so the entropy change will be negative.
Note we need to multiply the entropies of each substance by its coefficient in the balanced chemical equation.
Answer:
4.88 M
Explanation:
M = number moles/Volume (L)
MM AlCl3 = 133.34 g/mol
Volume = 500 mL = 0.5 L
number moles = mass/MM = 325.4/133.34 = 2.44 moles AlCl3
M = 2.44/0.5 = 4.88 M
