Description: The article refers to activity series. The author will cover something including what causes a redox reaction to happen, the definition of the activity series, how activity series can be used to predict whether a redox reaction will occur or not and the actual measured value or the force that causes some results to occur.
Today we’re going to be talking about the activity series, there is another tool that can be used when trying to learn and understand about redox or reduction oxidation reactions, so here’s a quick list of learning objectives that we’re going to cover.
First we’ll talk about what causes a redox reaction to happen, all chemical reactions are driven by certain forces acting within the chemistry, our job is to identify what forces are in a redox reaction, then talk about something known as reduction potentials which is the answer to that first question.
These will be the four sets of play here, last but not least, all of this information will be summarized in something known as the activity series, the activity series is a table and this is one version of that table here, you’ll need to find a copy of this at the bottom of the page and download this to having your notes.
But we’ll talk about what a definition of the activity series is, then ultimately how this activity series can be used to predict whether a redox reaction will or will not occur. When we looked at precipitation reactions, we use solubility rules to decide whether a precipitate will or will not form.
So we’ll begin with the discussion of what causes an actual redox reaction to occur or not and redox reactions are limited by each atoms ability to hold on to their electrons, if you recall in a redox reaction, there is an exchange of electrons from one atom to another, if one atoms pulling those electrons is not great enough to overcome, the other atoms pull the exchange which cannot occur.
As a result, the reaction cannot occur, so if the chemical being reduced the one that gains electrons pulls harder on electrons on the electrons than a chemical being oxidized, the one that loses electrons, then it has the ability to pull those electrons off the atom and cause a reaction to occur.
So again to recap the chemical being reduced the one that’s trying to gain electrons pulls harder onto those electrons than the one, that’s supposed to lose them, this reduced chemical can pull the electrons off the reaction happens and a result to get our redox reaction.
If that can happen, if this is pulled by the reducing substance is not great enough, then as a result of that, no reaction will occur, because neither atom has the ability to take electrons, offer the other one which if you recall is the driving force behind a redox reaction so to get more specific.
Then we can talk about the actual measured value or the force that causes this to occur, those are known as our reduction potentials, hopefully, the word potential is something remember from physics from last year, it’s a soft form of potential energy or the ability to do some work.
So what reduction potentials are is n deficit here, it is the tendency of an atom to attract electrons or to be reduced these stronger, your reduction potential is the better, you are being reduced which means the better oxidizing agents your particular substance is.
This is measured in volts like the potentials from back in physics are sometimes in millivolts, when you’re dealing with smaller substances, there are values we can have for that, the symbol we typically use for our reduction potentials is this e sub H value.
If those east of H values are positive, this means an attraction on electrons and that means your substance is more likely to be reduced or it is a better oxidizing agent, if the reduction potential is negative, that means the substance repels electrons, it’s more likely to be oxidized or lose them meaning it’s a better reducing agent so the magnitude of the number and the sign gives us an idea of whether we’ll be oxidized or reduced and how good it is doing that a bigger number equals stronger oxidizer or stronger reducing agent a positive.
Then what we’re able to do now is that we’re able to compare reduction potentials in different atoms to see if a redox reaction will occur, it’s a way of doing what we talked about previously of comparing how well this atom pulls on electrons versus how well that atoms holds on to its own ones is there enough of a difference in those forces that one atom can take electrons from the other.
If we were doing this in a more technical way, we could use the actual reduction of that are the reduction potential values and there’s some math that goes along with that, however, we can take all of this math and science and simplify it down to something known as the activity series.
So if the activity series is a list of elements or ions in order of decreasing reduction potentials and of cohere is decreasing by putting the elements in order, we can look at where an atom or ion shows up on the list and we can comparatively say whether it has a stronger or weaker reduction potential than atoms above it or below it.
So this is a tool that can be used to predict if a reaction will compare or will occur between two different compounds, if a substance is higher on the list, it is easier to oxidize, the more easily something is oxidized, the more likely we’ll get a reaction to occur.
The lower things are on the list which means they are more difficult to oxidize and they are less likely to react so more and less is probably the things I should have underlined here as opposed to circling the word react, we’re going to limit our rearm our Activity series table that looking at metals.
When you’re dealing with metals, these statements make a whole lot of sense, we’ll say over here, this is for metals only if you were going to be looking at a larger table of Activity series things, we have to generalize things a little more on this lesson more likely to react statements might not be quite as accurate.
So here’s an example of what an Activity series table can look like, what it’s basically showing you is the oxidation reactions of a bunch of different elements, we list the elements of the metal here in this column, we show the actual oxidation half-reaction lithium China into lithium +1 potassium and turned in class tascam plus 1.
These elements are listed in order of ease of oxidation the higher up on the table which are the easier, they are to oxidize and the more likely these substances are to react in a metal reaction or single replacement the ones in the bottom are less likely to occur.
As we already said, this table can be used to predict whether or not a reaction will occur the way we use, this is the part you need to be very careful about, write these down carefully, the element is to be oxidized in a single replacement reaction, that’s always going to be the element in the reaction.
There will always be something that’s an element when that thing is going to be oxidized, you got to find that on the periodic table, so find it listed are on the Activity series table, you’re also going to need to find the element that’s going to be reduced which in case of metal reactions, it’s typically the ion in your singular.
So you’ll find the elements that’s listed here and the ion to predict whether or not a reduction oxidation reaction will occur if the element is higher on the list, then you will get a reaction, if it’s the other way around, if the ions is higher on the list.
Then you get no chemical reaction and the way we’re able to simplify this down to such a simple statement is simply by putting these things in that correct order, it allows us simply to compare height on the table knowing they’re in order of reduction potentials, we can use that height as a way of comparing whether or not there is enough of a force to pull electrons off or not.
So we’re going to go through a couple of examples to show you how this works before we get into this, if it hasn’t already been obvious, you’re going to need a copy of this activity series table, there’s a link down below at the bottom of the page where you can download this particular one.
However, there are tons of these tables available online, any one of those tables will get the job done, they all work in the same kind of way, they all have very similar elements to the ones listed here, we’re going to start by taking a look at these two examples here.
In this case, we’re going to ask whether or not the reaction between magnesium and copper chloride is going to produce a product, so we got to identify the elements on the periodic table which in this case should be the elements magnesium that you’re looking for the thing with an oxidation state of zero.
We’re going to identify magnesium up here on the table itself, generally speaking, magnesium is fairly high up which means it has a relatively high ease of oxidation since it’s the metal that typically gets oxidized, that’s a good indication that this reaction is going to go forwards.
However, we also have to look for the ion, in this case, the ion is the copper ion, this is copper plus two in this scenario and copper shows up way down here on the table, so we said before, if the element magnesium is above the ion copper, then a reaction will occur.
There will be an exchange of electrons which will end up forming magnesium, if you look on your periodic table, the only other possible charge for magnesium is positive two and you can see that here as well, it turns to magnesium positive two, so that will make magnesium chloride mgcl2 and it form copper metal with a charge of zero I.
In this case, this single replacement redox reaction will indeed occur, we can continue this discussion with a second reaction gold metal reacting with hydrochloric acid, you’ll notice over here on the right or on the left, I mean gold shows up way over here on the bottom of your table, remember going up means ease of oxidation means gold is one of the most difficult metals to oxidize, that is not a good situation that we’re already in HCl.
We always have hydrogen, you notice it’s highlight in different color here, whenever we’re dealing with something reacting with acid which is very common, we use the hydrogen lime, remember the element has to be above the ion, this is our element with the oxidation state of zero.
This is our ion with an oxidation state of positive one, in this case, the ion is above the elements which means in this case, we will have no reaction and that is one of the properties that gold it has, it does not react with many other substances, that is one of the reasons, it’s such a valuable, a substance aside from its aesthetic value.
A Gold is very often used in electronics and high-intensity type of scenarios where you need a substance that is very resilient to chemical exposure, you might have noticed things like satellites, for example, being wrapped in gold foil that gold foil is a very high resilience covering that you can put on a satellite, that’s going to prevent it from being damaged by some of the ionizing radiation that occurs out in space that brings us to the end of our video on the activity series at this stage.
In the game, you should be able to describe the forces that cause or prevent a redox reaction from happening and those forces basically boil down to this particular idea reduction potentials, you should be able to describe to me what reduction potentials are.
I don’t expect you to look them up, I don’t expect you to do any work with reduction potentials simply that they are the driving force or the tendency of an atom to pull electrons away from other atoms which is what a redox reaction is.
Last but not least and probably most important of the three of them, you should be able to use the activity series in order to predict if a redox reaction will occur simply by using the table itself along with the simple rules that we created here.