Determine whether or not each redox reaction occurs spontaneously in the forward direction. a. Ca 2+ (aq) + Zn(s) → Ca(s) + Zn 2+ (aq) b. 2 Ag + (aq) + Ni(s) → 2 Ag(s) + Ni 2+ (aq) c. Fe(s) + Mn 2+ (aq) → Fe 2+ (aq) + Mn(s) d. 2 Al(s) + 3 Pb 2+ (aq) → 2 Al 3+ (aq) + 3 Pb(s)

hey everyone were given the below redox reaction. And we need to determine whether the four directions of this reaction is going to be spontaneous because we have a redox reaction. We should recognize that we're going to have two half reactions which come from our reactant. So for our first reactant we have barium two plus catalon which produces our product solid barium. We should recognize that we do have balance atoms. However, our net charge here is a plus two charge on the reactant side. Whereas on our product side we have a net neutral charge, meaning that we need to cancel out this plus two charge here on the reactive side by expanding our reactive side and adding two electrons to cancel out that plus two net charge. And so because we added electrons to our react inside, we would recognize that this half reaction occurs as a reduction. For our second half reaction, we have our second reactant which is our two moles of our sodium metal. And this is going to go ahead and form our product two moles of the carry on of sodium. And so what we should recognize is that we do have balanced atoms. We have two atoms of sodium on both sides. However, we have a net Charge of Plus one on the product side here and so on our reactive side, we need that to match with our net charge of zero. So we want to cancel out this net charge of we have a coefficient of two times plus one which would actually give us a charge of plus two, which we would cancel out by adding two electrons here on the product side. And because we added electrons to our product side, we would recognize that this half reaction occurs as an oxidation. So our next step is to recall that our reduction half reaction occurs at the cathode of our voltaic cell, whereas our oxidation half reaction will occur at the an ode of art voltaic cell. And so our next step is to recall our standard reduction potential table where we would see for the oxidation of our Barium two Plus Catalon, we're going to have a self potential value Equal to -2.90V at our cathode. Whereas for our oxidation of our sodium catalon according to this table, we're going to have a cell potential value Equal to negative 2.71V for our node. And so now we can go ahead and calculate our standard cell potential equal to our self potential of our cathode. Subtracted from our self potential of our an ode. So this is something that we should recall. And we're going to plug in our known values from above. So we would get that our standard cell potential value is equal to our self potential of our cathode which above we stated is equal to a value of negative 2.90V subtracted from our self potential of our node, which will plug in from above As -2.71V. And this is going to give us a standard cell potential value equal to negative 0.19V according to our calculators. And so what we should recall now is that when we have a standard cell potential value that is less than zero. This means that our reaction is going to be non spontaneous in the forward direction. And so because we can agree that our self potential value, Which we stated is equal to negative 0.19V is less than zero. We can say therefore our reaction, we can say therefore no, our reaction is not spontaneous, it's going to occur non spontaneous in the forward direction. And so for our final answer, we can confirm our self potential value here means that our reaction is going to be non spontaneous in the forward direction and just so that's visible, just scoot this over a bit. So I hope that everything I explained was clear. If you have any questions, please leave them down below. Otherwise, I'll see everyone in the next practice video

Ch.19 - Electrochemistry

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Tro 4th Edition

Ch.19 - Electrochemistry

Problem 54

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Chapter 19, Problem 54

Determine whether or not each redox reaction occurs spontaneously in the forward direction.
a. Ca²⁺(aq) + Zn(s) → Ca(s) + Zn²⁺(aq)
b. 2 Ag⁺(aq) + Ni(s) → 2 Ag(s) + Ni²⁺(aq)
c. Fe(s) + Mn²⁺(aq) → Fe²⁺(aq) + Mn(s)
d. 2 Al(s) + 3 Pb²⁺(aq) → 2 Al³⁺(aq) + 3 Pb(s)

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Identify the oxidation and reduction half-reactions. In this case, silver ions (Ag+) are reduced to silver metal (Ag), and nickel metal (Ni) is oxidized to nickel ions (Ni2+).

Write the half-reactions separately. For reduction: Ag+ + e- → Ag. For oxidation: Ni → Ni2+ + 2e-.

Check the standard reduction potentials for each half-reaction. The standard reduction potential for Ag+ to Ag is +0.80 V, and for Ni to Ni2+ it is -0.25 V.

Calculate the standard cell potential (E°cell) for the reaction by subtracting the standard reduction potential of the anode (oxidation) from the cathode (reduction). E°cell = E°cathode - E°anode.

Determine the spontaneity of the reaction. If E°cell is positive, the reaction is spontaneous in the forward direction; if it is negative, the reaction is non-spontaneous.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Redox Reactions

Redox reactions, or reduction-oxidation reactions, involve the transfer of electrons between two species. In these reactions, one species is oxidized (loses electrons) while the other is reduced (gains electrons). Understanding the oxidation states of the elements involved is crucial for identifying which species undergo these changes.

Standard Electrode Potentials

Standard electrode potentials (E°) are measured values that indicate the tendency of a species to be reduced. Each half-reaction has a specific E° value, and the overall spontaneity of a redox reaction can be determined by calculating the cell potential (E°cell) using the formula E°cell = E°(reduction) - E°(oxidation). A positive E°cell indicates that the reaction is spontaneous in the forward direction.

Spontaneity of Reactions

The spontaneity of a reaction refers to its ability to occur without external intervention. In the context of redox reactions, spontaneity can be assessed through Gibbs free energy (ΔG). A negative ΔG corresponds to a spontaneous reaction, which can be related to the cell potential; specifically, ΔG = -nFE°cell, where n is the number of moles of electrons transferred and F is Faraday's constant.