In the first law of thermodynamics, △E = Q-w, what does △E stand for?
2 answers:
<u>Answer: </u>The correct answer is Option B.
<u>Explanation:</u>
First law of thermodynamics states that the energy can neither be destroyed not be formed but it can only be transformed from one form to another.
Here, the internal energy of the system is being transformed to the heat energy and the work done by the system. The equation used to represent first law of thermodynamic is:
where,
represents the internal energy of the system.
Q = heat released or absorbed by the system.
w = work done by or on the system.
Hence, the correct answer is Option B.
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Answer:
E°cell = - 1.3575 V
This reaction is spontaneous in the reverse direction
Explanation:
The given cell reaction:
Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)
The given Gibbs free energy: ΔG = 131 kJ = 131 × 10³ J (∵ 1 kJ = 10³ J)
As we know,
ΔG = - n F E°cell
Here, n - the number of moles of electrons transferred = 1
F - Faraday constant = 96500
E°cell - cell potential = ?
<u>For a given chemical reaction if-</u>
1. ΔG = negative and E°cell = positive
⇒ <em>The reaction is spontaneous and proceeds spontaneously in the forward direction.</em>
2. ΔG = positive and E°cell = negative
⇒ <em>The reaction is non-spontaneous and proceeds spontaneously in the reverse direction.</em>
<u>Since, for this chemical reaction: </u>
Cr³⁺(1.32 × 10⁻³ M) + Fe²⁺(aq) → Cr²⁺(aq) + Fe³⁺(1.14 M)
ΔG = + 131 × 10³ J ⇒ positive
and, E°cell = - 1.3575 V ⇒ negative
<u>Therefore, this reaction is spontaneous in the reverse direction.</u>