Question

1) Given the following thermochemical reaction and thermodynamic data, find Gibbs Free Energy, ΔG, and determine if the reaction is spontaneous or non-spontaneous at 25 °C?

N2(g) + 3H2(g) → 2NH3(g) ΔH = -91.8 kJ

ΔS[N2] = 191 J / mol · K, ΔS[H2] = 131 J / mol · K, and ΔS[NH3] = 193 J / mol · K

a.98.3 kJ; Non-Spontaneous

b.-98.3 kJ; Spontaneous

c.32.7 kJ; Non-Spontaneous

d.ΔG = -32.7 kJ; Spontaneous

2) What is the oxidation number for selenium in the Selenate Ion, SeO₄^-2?

a.	+6
	b.	+3
	c.	-3
	d.	-6

3) Given the following electrochemical reaction, identify the reducing agent.

2Al(s) + 3F₂(g) → 2AlF₃(s)

a.

Fluorine (F₂)

b.

Aluminum (Al)

c.

Aluminum Fluoride (AlF₃)

4) Calculate the cell potential, E°_cell, for the following electrochemical reaction.

Cu(s) + I₂(g) → Cu⁺²(aq) + 2I^-1(aq) E = ?

a.-0.87 V

b.-0.19 V

c.0.19 V

d.0.87 V

Answer 1

Answer)1.For reaction,,

Now,

∆S = (∆S of product ) - (∆S of reactant)

= (2× 193) - (191+ 3×131)

= - 198 J/ mol K

= - 0.198 kJ / mol K

Now,,

T = 25+273 = 298 K

So , putting the values in above equation,,

Negative sign indicates that , it is a spontaneous reaction.

So, option (d) is the correct answer.

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Answer)2. Option (a) is the correct answer.

SeO₄^2-

Se + (-2)×4 = -2

Se = +6

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Answer)3. Option (b) is the correct answer.

Aluminium is the reducing agent, because it is oxidized in the reaction and reduce the fluorine .