Chemical Oxidization Question

Question

Given the following equation, identify the chemical being oxidized, the chemical being reduced, the oxidizing agent, and the reducing agent.

Na(s) + Ag^+(aq) --> Na^+(aq) + Ag(s)

I need help, so I can understand how to do it. Thank you!

Answer 1

So before solving this problem we must understand the terms that are being used:

1. Oxidized chemical: or an oxidation is the process in which one or more electrons is loss by a substance even if the element, compound, or ion status
2. Reduced chemical: or reduction is the process in which one or more electrons is gained by a substance.
3. Oxidation-reduction reaction (redox) is any process in which electrons are transferred from one substance to another.
4. Oxidizing agent: is the substance that causes oxidation, gains one or more electrons, undergoes reduction, and the oxidation number of the atoms decreases
5. Reducing agent: is the substance that causes reduction, loses one or more electrons, undergoes oxidation, and its oxidation number of the atom increases.

So looking at this equation we first have to make sure its balanced (which assuming we are) is, if it wasn't we would have to balance it by adding electrons on either side of the equation, etc. Next we have to under go redox rules:

1. An atom in its elemental state has an oxidation number of 0.
2. An atom in a monatomic ion has an oxidation number identical to its charge
3. An atom in a polyatomic ion or in a molecular compound usually has the same oxidation number it would have if it were a monatomic ion
4. Hydrogen can either be a negative or positive one
5. Oxygen usually has an oxidation number of -2
6. Halogens usually have an oxidation number of -1
7. The sum of the oxidation numbers is 0 for a neutral compound, and is equal to the net charge for a polyatomic ion.

Now lets breaks our main equation into two separate equations:

Na (s) ---> NA+ (aq) this is similar to A---> A+ (oxidation) O charge ----> +1 charge

Ag+ (aq) ---> Ag (s) this is similar to A+--->A (reduction) +1 charge -----> O charge

Applying the rules as stated above to the first equation; i see that my Na is in its natural element (solid) and thus has an oxidation number of zero but looses an electron and becomes more positive in an aqueous solution and thus is undergoing an oxidation and is causing a reduction. In my second equation I'm starting out more positive and underling up with a zero charge thus i am gaining electrons and becoming "more negative" thus its causing an oxidation and is being reduced.

Thus may Na is undergoing oxidation and is therefore my reducing agent because it overall causes reduction.

That means my Ag is undergoing reduction and is therefore my oxidizing agent because it overall causes oxidation.

Another way to looks at this problem is through Standard reduction potentials which uses the same concepts for redox reactions. In this cause the two equations we formed will look like this:

Ag+ (aq) + e- ---> Ag (s)

Na+ (aq) + e- ----> Na (s)

In this fashion my oxidizing agent is Ag because this is an extremely strong oxidizing reagent because we are going in the foreword (favored) direction. However, in the second equation, we are going backwards, thus because of this Na is a stronger reducing agent (weak oxidizing agent). When looking at the standard reduction potential table since Ag lies above Na, Ag can only oxidize those that are below it and in this case Na lies below and since Na is on the bottom of the chart it can only reduce those that are above it which the is the case (this table can be seen in any chemistry textbook for reference).