Activity Series - Online Tutor, Practice Problems & Exam Prep

In chemistry, understanding the activity series of metals is crucial for predicting the outcomes of single displacement reactions, where one element replaces another within a compound. Elements higher on the activity series chart can displace those below them to form new compounds. For instance, lithium, being at the top of the series, can displace any element below it. The activity series also indicates that certain metals can displace hydrogen from compounds like liquid water, steam (water vapor), or acids ($H_{3}O+$). The position of hydrogen in the series acts as a benchmark, separating metals that can displace hydrogen from those that cannot. As one moves down the series, the ability of an element to displace others decreases, reflecting a reduction in reactivity. This hierarchy is essential for understanding chemical reactivity and reaction predictions in displacement reactions.

Activity Series

In this new set of videos, we're going to take a look at activity series. But first we need to realize what a single displacement reaction is. It's basically when one element replaces another element within a compound. So for the simplicity, we say that we have an element A and it's trying to replace one of the elements within the compound BC. Let's say that it wants to replace B. It would literally remove B, kick B out, and so now we'd have a new compound AC with B over here.

Now, not any element can replace or displace another element from a compound. To determine which ones can we utilize the Activity Series chart. This chart determines if an element can displace another element. Now we're going to say an element higher in the activity series chart. We'll displace an element below it in the series.

So just remember, a single displacement reaction, one element replaces another within a compound to create a whole new compound. And we're going to utilize an activity series chart to see which elements can displace other ones. So click on to the next video and let's take a look at this Activity series chart.

Activity Series

Before we have the activity series chart, so let's take a quick look at it. Realize first that as we go up, the activity series strength increases. And we need to realize here that this first group in red, lithium, potassium, barium, strontium, calcium, sodium, they're above all the other groups, so they can displace any of those. And within that group, since lithium is the highest, it can displace any of the elements below it.

So remember we set the higher up you are in terms of the activity series chart, the easier it is for you to displace the elements below you. We also realize here that we have hydrogen gas kind of as like a border that helps to separate these. Below this border we have these elements here which cannot really displace hydrogen. So if hydrogen is connected to another element, they won't be able to kick out the hydrogen and bond with that other element.

Now here we can talk about what these other groups can do. How can they displace H₂? So basically they can replace hydrogen for the first group if it's in the form of liquid water. If it's in the form of gas, well, not liquid gas, water vapor, which we call steam. And then finally if it's in the form of an acid as H₃O⁺. OK, so they can displace hydrogen from any of these forms. They can also displace elements below them.

And as we go down, we see that the activity strength is decreasing. So these could only displace hydrogen if it's found in liquid water or if it's found in gaseous vapor. And then as you can see, we're just going down, down, down what they're able to do. These could only displace it from H₃O⁺, which is our acid. So just remember, we're going to be looking at these elements in their activity series to see how they can displace another element.

Activity Series Example 1

In this example question it says a very common example is the displacement of a hydrogen atom by magnesium when reacting with hydrochloric acid. Based on your understanding of the activity series chart, determine the products formed. All right, so magnesium is a metal. Remember metals are monoatomic and naturally exist as solids. Then we have hydrochloric acid HCL. Also recall when we talked about solubility in electrolytes, that acids exist in the aqueous form.

Here we're talking about displacing hydrogen by magnesium. That's what they tell us. So that means that magnesium is going to kick out basically hydrogen from HCL. That means we're going to have a metal, magnesium with a nonmetal chlorine. Remember, metal plus nonmetal means it's ionic and ionic compound. So we need their charges. Magnesiums in Group 2A, so it's charges 2 plus chlorine is in Group minus group 7A, so it's -1. Remember, when the numbers in the charges are different, they don't cancel out, they crisscross. So two comes here and one comes here. So we'd have here magnesium chloride aqueous.

Now hydrogen gets displaced. When it gets displaced, it becomes its natural form. So the natural form of hydrogen is H₂ and remember hydrogen exists as a gas in its natural form. If you don't recall that, make sure you go back and take a look at my videos. When we talk about periodic table and elemental forms, all we need to realize here now is that on the product side we have two chlorines and two hydrogens. So to balance this out I just need to put a 2 here for HCL. So this we would represent my equation after magnesium has displaced hydrogen from hydrochloric acid.

Mg 2 + + Cl 1 - → MgCl 2 + H 2

Based on your understanding of activities determine if a reaction occurs and if so provide the products formed. 

Ba (s) + H₂O (g) →

• A. Ba (s) + 4 H₂O (g) → Ba(OH)₂ (aq) + 2 H₂ (g)
• B. Ba (s) + H₂O (g) → Ba(OH)₂ (aq) + H₂ (g)
• C. Ba (s) + 2 H₂O (g) → Ba(OH)₂ (aq) + H₂ (g)
• D. No reaction

Based on your understanding of activities determine if a reaction occurs and if so provide the products formed. 

Zn (s) + NiCl₂ (aq) →

• A. Zn (s) + 2 NiCl₂ (aq) → ZnCl₂ (aq) + 2 Ni (s)
• B. Zn (s) + NiCl₂ (aq) → 2 ZnCl₂ (aq) + Ni (s)
• C. Zn (s) + NiCl₂ (aq) → ZnCl₂ (aq) + Ni (s)
• D. No reaction

If the activity of halogens is stated as:Fluorine > Chlorine > Bromine > Iodine, determine if a reaction occurs and if so provide the products formed. 

Cl₂ (g) + AlBr₃ (aq) →

• A. 3 Cl₂ (g) + 2 AlBr₃ (aq) → 2 AlCl₃ (aq) + 2 Br₂ (l)
• B. 3 Cl₂ (g) + 2 AlBr₃ (aq) → 2 AlCl₃ (aq) + 3 Br₂ (l)
• C. 3 Cl₂ (g) + AlBr₃ (aq) → AlCl₃ (aq) + 3 Br₂ (l)
• D. No reaction

Here’s what students ask on this topic:

What is the information used for on the activity series?

The activity series is a chart that scientists use to predict the reactivity of metals with other substances, including acids and other metal salts. It lists metals in order of decreasing reactivity, meaning that metals at the top of the series are more reactive than those at the bottom. This information is particularly useful in chemistry for determining the outcome of single displacement reactions, where one metal replaces another in a compound.

For example, if you have a reaction where magnesium is added to a solution of copper sulfate, you can use the activity series to predict that magnesium will displace copper from the compound because magnesium is higher in the series. This is because magnesium is more reactive and can more easily lose electrons to form positive ions. The activity series helps you understand which metals can displace others from solutions, which is crucial for synthesizing compounds, understanding corrosion, and performing quantitative analysis in chemistry.

How does the activity series work?

The activity series, also known as the reactivity series, is a list of elements, typically metals, arranged in order of decreasing reactivity. It predicts how metals will react with water, acid, and other substances, and it determines which metal will displace another in a single displacement reaction.

At the top of the activity series are the most reactive metals, like lithium, potassium, and calcium. These metals will react even with cold water, releasing hydrogen gas and forming hydroxides. As you move down the series, metals become less reactive. For example, magnesium reacts with steam but not cold water, and metals like iron will only react with strong acids.

The activity series is also useful in predicting the outcomes of displacement reactions. A metal higher in the series will displace a metal ion in a solution that is lower in the series. For instance, zinc can displace copper ions from copper sulfate solution because zinc is higher in the activity series than copper. Understanding the activity series is crucial for predicting the results of chemical reactions involving metals.

What is the activity series?

The activity series, also known as the reactivity series, is a list of elements, particularly metals, organized in order of decreasing reactivity. In the context of chemical reactions, the activity series predicts which metals will displace other metals in single displacement reactions, where a more reactive metal will replace a less reactive metal in a compound.

For example, if you have a solution of copper sulfate and you add a piece of zinc metal, the zinc will displace the copper because zinc is higher in the activity series. The series starts with the most reactive metals, such as alkali metals like lithium and potassium, and descends to less reactive metals, including transition metals like copper and gold. The activity series is a valuable tool for predicting the outcomes of reactions and understanding the tendencies of metals to lose electrons and form positive ions (cations).

How can the activity series be used?

The activity series, also known as the reactivity series, is a list of metals arranged in order of decreasing reactivity. It is used to predict the outcomes of single displacement reactions, where one metal displaces another from a compound. For example, if you have a metal reacting with the ions of another metal in a solution, the activity series can tell you whether a reaction will occur based on the relative reactivity of the two metals.

If a metal is above another in the series, it is more reactive and can displace the lower metal from its compounds. For instance, if you place a strip of zinc into a copper sulfate solution, zinc, being higher in the activity series, will displace the copper and form zinc sulfate. Conversely, if you place copper into a zinc sulfate solution, no reaction will occur because copper is less reactive than zinc.

The activity series is also useful in predicting the products of reactions, understanding the reactivity of metals with water and acids, and in electrochemistry for determining the direction of electron flow in galvanic cells.