contestada

Classify each of the following reactions as one of the four possible types:

1. spontaneous at all temperatures;
2. nonspontaneous at all temperatures;
3. spontaneous at low T; nonspontaneous at high T;
4. spontaneous at high T; nonspontaneous at low T.

(a) N2(g)+3F2(g)→2NF3(g); ΔH∘=−249kJ;ΔS∘=−278J/K
(b) N2(g)+3Cl2(g)→2NCl3(g); ΔH∘=460kJ;ΔS∘=−275J/K
(c) N2F4(g)→2NF2(g); ΔH∘=85kJ;ΔS∘=198J/K

Respuesta :

Explanation:

Using Gibbs Helmholtz equation:

[tex]\Delta G^o=\Delta H^o-T\Delta S^o[/tex]

  • ΔG° = negative (spontaneous)
  • ΔG° = positive (non spontaneous)

a)[tex]N_2(g)+3F_2(g)\rightarrow 2NF_3(g)[/tex]

ΔH°=-249 kJ = -249000 J , ΔS°=-278J/K

[tex]\Delta G=\Delta H-T(-ve)[/tex]

[tex]\Delta G=(-ve)+(ve)[/tex]

[tex]\Delta G=(-ve)[/tex] (at low Temperature)

[tex]\Delta G=(+ve)[/tex] (at high Temperature)

Spontaneous at low Temperature , Non-spontaneous at high Temperature;

b) [tex]N_2(g)+3Cl_2(g)\rightarrow 2NCl_3(g)[/tex]

ΔH°=460kJ = 460,000 J, ΔS°=-275 J/K

[tex]\Delta G=\Delta H-T(-ve)[/tex]

[tex]\Delta G=(+ve)+(+ve)[/tex]

[tex]\Delta G=(+ve)[/tex]

Non spontaneous at all temperatures.

(c) [tex] N_2F_4(g)\rightarrow 2NF_2(g)[/tex]

ΔH°= 85kJ 85,000 J , ΔS°= 198J/K

[tex]\Delta G=\Delta H-T(+ve)[/tex]

[tex]\Delta G=(+ve)-(+ve)[/tex]

[tex]\Delta G=(+ve)[/tex] (at low temperature)

[tex]\Delta G=(-ve)[/tex] (at high temperature)

Spontaneous at high Temperature non-spontaneous at low temperature.

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