You want to “plate out” nickel metal from a nickel nitrate...

Key Concepts

Activity Series of Metals

The activity series is an arrangement of metals (and hydrogen) ordered by their reactivity, particularly their tendency to lose electrons and oxidize. Metals lower in the series are more reactive and will displace metals that are higher in the series from their solutions, making them suitable for processes where plating occurs through such spontaneous redox reactions.

Standard Electrode Potentials

This concept involves the inherent tendency of different metals to gain or lose electrons, measured as reduction potentials. In redox reactions, the difference in these potentials determines which species will be oxidized and which will be reduced. A metal with a lower (more negative) reduction potential is more prone to oxidation and can thus reduce ions of a metal with a higher (more positive) potential.

Displacement (Redox) Reactions

These reactions occur when a more reactive metal displaces a less reactive metal from its compound in solution. The more active metal is oxidized in the process, donating electrons to reduce the metal ions to their elemental form, which then deposit on the surface of the more reactive metal.

Electroplating

Electroplating is the process of depositing a thin layer of metal onto a substrate through the reduction of metal ions in a solution. It can occur via an external electrical current or through a spontaneous redox reaction where a more reactive metal reduces ions of a less reactive metal, leading to seamless metal deposition.

Transcript

00:01 Hello, my name is margaret, and today i'm going to be talking to you about problem five in zoomdahl chapter 18, which is about electrochemistry.

00:12 And just for a quick recap of the problem, i have here, it says that you want to plate out nickel, metal from a nickel nitrate solution onto a piece of metal inserted into the solution, should you use copper or zinc? explain.

00:32 And so what i'm assuming they mean here is that they're, so if we just start drawing it out, if we have, let me draw that a little bit bigger.

01:07 So if we have this beaker here that's going to be our cell, and we have our piece of metal right here, and that's our electrode lead.

01:21 Nickel nitrate is nickel 2 plus, and here are our two nitrates, voting around in solution as counter ion.

01:35 And what i'm assuming they are trying to say is they're asking what metal should this piece be right here.

01:47 So they're asking, should this be copper or think question mark? and i'm going to try and remember to put these little tabby's on my z's to distinguish them from the twos for this video.

02:04 I normally don't do that, but i want to make sure you guys can tell the difference.

02:09 So let's kind of piece through the wording or nomenclature in this problem.

02:16 So that way, we're clear on what they're asking.

02:20 So when they say plate out, what they're really saying is make a solid.

02:35 Okay.

02:36 When we are doing this kind of electrochemistry here where we have put a piece of metal in solution, this is a cent.

02:47 We call this our working electrode.

02:50 It's a fancy term that electrochemists use.

02:54 But basically all of the ions are going to come to this surface for that to occur in order to do that electron exchange.

03:07 And so we, as opposed to the solidification happening in the out inside the solution and the solid falling to the bottom of the beaker, it's going to occur on the service dealer.

03:20 Electrode and the solid will stick to the surface of the electrode.

03:25 And that's how you get metal coatings on things.

03:28 And so that's why we call it plating out, is we are going to literally create a plate of nickel onto the surface of our metal.

03:36 So now that we know that we're talking about making a solid, we are starting out with an ion, and we are going to make it a solid.

03:48 So that means that we are talking about reduction.

03:57 So if we are talking about reduction, what we really want to know is, and we're comparing nickel to copper and zinc.

04:12 What is a wonderful chart we know of where we can compare different reductions of things? well, what about standard reduction? potentials.

04:32 How convenient, right? so what we really want to know is who has the most negative, or actually, i'm sorry, not the most negative.

04:57 Who has the actually the least negative? now, why am i phrasing it like this? why am i not saying the most positive? there's a reason for this.

05:13 I, if you've watched some of my other videos, you might have heard me mention that i am, i myself am an electrochemist.

05:22 And the reason why i harp on this is because electrochemists in general talk only in terms of reductions.

05:31 And there is a reason we do that.

05:34 It's so we don't confuse ourselves.

05:37 And the reason why we stick with reductions in particular is because of the standard reduction potentials chart.

05:47 You can do the whole flip it around, flip the sign thing, but then you have to be careful because a lot of the equations that we use are standardized specifically for being written for standard reduction potential.

06:06 Or being written for reductions in general.

06:09 So in order to keep everything, in order to give me the best chance of being able to not mess up and solve the problem correctly, and i mean to this day, in the lab, when i'm trying to work, i always keep things in reductions, and that's even if i'm talking about oxidations that i'm doing.

06:34 And it served me well in high school, it served me well in college and it's still serving me well in graduate school.

06:40 So that's why i really recommend that...

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