A metal salt with the formula MSO4 crystallizes from water to form a solid with the composition MSO4⋅3H2O. At 298 K, the equilibrium vapor pressure of water above this solid is 14.7 Torr. MSO4⋅3H2O(s)↽−−⇀MSO4(s)+3H2O(g) What is the value of ΔG for the reaction when the vapor pressure of water is 14.7 Torr?

Respuesta :

Answer:

ΔG =  6259.11 kJ/mol

Explanation:

At 298 K, the equilibrium vapor pressure of water above this solid is 14.7 Torr.

MSO4⋅5H2O(s)⇔ MSO4(s)+5H2O(g)

→ 1 atm = 760 torr

So, 14.7 torr= 0.0193 atm = 0.0193 / 760

Kp = [p(H2O)]3  

= ( 0.0193/760)³

= 1.637 x 10^-14

as we know that, by Kp and Kc reaction

Kp = Kc (RT)^Δng

Δng = 3 -0  = 3

Kc = Kp / (RT)³

= 1.637 x 10^-14 / (0.082 x 298)³

=  1.637 x 10^-14  / 14,591.177

1.12237 x 10^-18

What is the value of Δ for the reaction when the vapor pressure of water is 14.7 Torr?

we have, Δ = - RT ln K

Δ = - (8.314 J/K-mol × 298) ln 1.12237 x 10^-18

= 2477.57 x  ln 1.12237 x 10^-18

= 2477.57 x 2.5263

= 6259.11 kJ/mol

The value of ΔG for the reaction when the vapor pressure of water is 14.7 Torr is 6259.11 kJ/mol.

What is ΔG?

The ΔG is the change in free energy of a system that goes from initial state to final state.

Also known as Gibbs free energy.

Given,

At 298 K, the equilibrium vapor pressure of water above the solid is 14.7 Torr.

The reaction is

[tex]\rm MSO_4.3H_2O(s) <=>MSO_4(s)+3H_2O(g)[/tex]

1 atm = 760 torr

So, 14.7 torr = [tex]\dfrac{14.7}{760\;torr} = 0.0193\; atm.[/tex]

By the formula of the equilibrium constant

[tex]Kp = [p(H_2O)]^3 \\\\Kp= [0.0193]^3 =1.637 \times 10^-^1^4[/tex]

We know that Kp = Kc

[tex]Kp = Kc (RT)^\Delta^n^g[/tex]

Δng = 3 -0  = 3

[tex]Kp = \dfrac{ Kc}{(RT)^3}[/tex]

Putting the values

[tex]Kp = \dfrac{ 1.637 \times 10^-14 }{(0.082 \times 298)^3}\\\\Kp= \dfrac{ 1.637 \times 10^-14 }{14,591.177}\\\\ =1.12237 \times 10^-18[/tex]

Now, Δ = - RTlnK

[tex] \Delta = - (8.314 J/K-mol \times 298) ln 1.12237 \times  10^-^1^8 [/tex]

[tex] = 2477.57 \times ln 1.12237 \times 10^-^1^8 [/tex]

= 2477.57 x 2.5263

= 6259.11 kJ/mol

Thus, The value of ΔG for the reaction when the vapor pressure of water is 14.7 Torr is 6259.11 kJ/mol.

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