When does displacement reaction occur

The elements on top of the column will replace the elements below them on the periodic table but not the other way around. Thus, the reaction represented by. This is just one of many ways the periodic table helps us understand chemistry.

Will a single-replacement reaction occur? If so, identify the products. Yes; FeCl 2 and I 2. Chemical reactivity trends are easy to predict when replacing anions in simple ionic compounds—simply use their relative positions on the periodic table.

However, when replacing the cations, the trends are not as straightforward. This is partly because there are so many elements that can form cations; an element in one column on the periodic table may replace another element nearby, or it may not. A list called the activity series does the same thing the periodic table does for halogens: it lists the elements that will replace elements below them in single-replacement reactions.

A simple activity series is shown below. Using the activity series is similar to using the positions of the halogens on the periodic table. An element on top will replace an element below it in compounds undergoing a single-replacement reaction.

Elements will not replace elements above them in compounds. Use the activity series to predict the products, if any, of each equation. Use the activity series to predict the products, if any, of this equation. A double-replacement reaction occurs when parts of two ionic compounds are exchanged, making two new compounds. A characteristic of a double-replacement equation is that there are two compounds as reactants and two different compounds as products.

An example is. There are two equivalent ways of considering a double-replacement equation: either the cations are swapped, or the anions are swapped. You cannot swap both; you would end up with the same substances you started with. Either perspective should allow you to predict the proper products, as long as you pair a cation with an anion and not a cation with a cation or an anion with an anion.

Thinking about the reaction as either switching the cations or switching the anions, we would expect the products to be BaSO 4 and NaCl. Predicting whether a double-replacement reaction occurs is somewhat more difficult than predicting a single-replacement reaction. And, in this case, copper also has valency 2. So, to fullfill their 'octet' requirements, they both react. The problem is: Suppose we take the metal zinc and bring it in contact with copper sulfate.

Now, a displacement reaction occurs, in which zinc replaces copper because of its higher reactivity. Copper sulfate is a compound that is neutral; both the cation and anion have completed their octets; why then does zinc replace copper? Or, in other words, after completing the octet, why it is necessary for sulfate to leave copper and react with zinc?

It is due to that zinc is more reactive than copper which is less reactive metal so, zinc can easily displaces copper from its solution. Also, we can also consider the electrochemical series or activity series to give a better reason for the same. In activity series, zinc has greater value of standard reduction potential than copper's standard reduction potential value.

It means, zinc can easily reduce Copper and it get oxidised. Sign up to join this community. Now you might be wondering, Ram, how am I supposed to know which element is more reactive than the other? So for this scientists have been doing a lot of experiments, a lot of reactions and they have prepared a list. They have listed down, they have organized all the elements or most of the elements in order of their reactivity.

So this is the reactivity series. While it does not have all the elements but the ones that we are going to use the most. Now see, in this series the element that is higher up is going to be more reactive than the element that is lower in the series.

For example here calcium, calcium is above oh, let's say, aluminum. So calcium is more reactive than aluminum and it can displace aluminum from it's compound. Whereas calcium is lower than sodium in the series. That means sodium is more reactive than calcium or calcium is less reactive.

That means sodium can displace calcium. Now with the help of the series, let's try to solve a couple of more problems. So here I have two reactions. Now I want you to pause the video and see that which reaction will proceed and which won't and also write down the products of it. So in this first reaction we have hydrogen. So hydrogen is somewhere here in this list and then we have magnesium chloride. So magnesium is somewhere higher up in the list, that means that magnesium is more reactive than hydrogen.

Hydrogen is less reactive so that means hydrogen cannot displace magnesium and this reaction is not going to go further. This will not go further.

Whereas here if you see, iron is somewhere here and copper chloride. So copper is somewhere here. Okay, copper is lower than iron.

That means iron is more reactive. And since iron is more reactive, it can displace copper from it's chloride. And finally we will get iron chloride and copper will be displaced. Copper will be displaced. So now, you might be wondering, Ram, how do I remember this long series of so many elements? So for this, I use a mnemonic. I call it the careless zebra mnemonic. It's read as, please stop calling me a careless zebra, instead try learning how copper saves gold.

So now you can see that the first letter of please can help you remember potassium. And the first letter of stop can help you to remember sodium and so on and so forth. So with this series in mind, you will be able to remember the reactivity series.

Now once again let's see. Here are the equations for the reaction:. No reaction is seen if you do things the other way round — in other words, if you put copper powder into magnesium sulfate solution. This is because copper is not reactive enough to displace magnesium from magnesium sulfate. You can investigate the reactivity of metals using displacement reactions. The table shows the results from a series of experiments involving four metals and solutions of their salts.