Activity Series: Videos & Practice Problems

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.

Single Displacement Reactions

In chemistry, a single displacement reaction occurs when one element replaces another element in a compound. This can be illustrated with a simple example: if element A attempts to replace element B in the compound BC, it effectively removes B, resulting in a new compound AC, while B is left as a free element. However, not all elements can replace others; the ability to do so is determined by the activity series chart.

The activity series is a list that ranks elements based on their reactivity. An element positioned higher in the activity series can displace an element that is lower in the series. This means that if element A is above element B in the activity series, A can successfully replace B in the compound. Understanding this concept is crucial for predicting the outcomes of single displacement reactions and determining which reactions will occur.

In summary, single displacement reactions involve the replacement of one element in a compound by another, and the activity series chart is an essential tool for identifying which elements can participate in these reactions.

Activity Series Chart

The activity series is a crucial tool in understanding the reactivity of metals and their ability to displace other elements in chemical reactions. As you move up the activity series chart, the strength of reactivity increases. The top group, highlighted in red, includes lithium, potassium, barium, strontium, calcium, and sodium. These metals are capable of displacing any elements located below them in the series. Notably, lithium, being the highest in this group, can displace all other elements beneath it.

A key feature of the activity series is the presence of hydrogen gas, which acts as a boundary. Elements positioned below hydrogen in the series cannot displace it from compounds. For instance, if hydrogen is bonded with another element, those lower elements cannot replace hydrogen in a reaction.

When considering how certain metals can displace hydrogen, it is important to note that the first group can do so in various forms: liquid water, water vapor (steam), or in acidic solutions represented as H₃O⁺. This means that metals like lithium and potassium can effectively replace hydrogen in these states. As you descend the activity series, the ability to displace hydrogen diminishes. For example, metals lower in the series can only displace hydrogen when it is present in liquid water or as a gas, while even lower metals can only displace hydrogen from acidic solutions.

Understanding the activity series allows for predicting the outcomes of displacement reactions, emphasizing the importance of the position of each element within the series. This knowledge is essential for analyzing chemical reactivity and the potential for displacement in various chemical contexts.

Activity Series Chart Example

In the reaction between magnesium and hydrochloric acid (HCl), magnesium displaces hydrogen due to its higher reactivity, as indicated by the activity series of metals. Magnesium, a solid metal, reacts with the aqueous form of hydrochloric acid, resulting in the formation of magnesium chloride and hydrogen gas.

The balanced chemical equation for this reaction can be derived as follows:

1. Identify the reactants: magnesium (Mg) and hydrochloric acid (HCl).

2. Recognize that magnesium will displace hydrogen from HCl, leading to the formation of magnesium chloride (MgCl₂) and hydrogen gas (H₂).

3. Determine the charges of the ions involved: magnesium has a charge of +2 (as it is in group 2A), while chlorine has a charge of -1 (as it is in group 7A). To form magnesium chloride, the charges must balance, resulting in the formula MgCl₂.

4. The displacement of hydrogen means that it will be released in its diatomic form (H₂), which is a gas at room temperature.

5. To balance the equation, since two chlorine atoms are produced in magnesium chloride, we need two hydrochloric acid molecules to provide the necessary chlorine and hydrogen atoms:

2 HCl (aq) + Mg (s) → MgCl₂ (aq) + H₂ (g)

This balanced equation illustrates that two moles of hydrochloric acid react with one mole of magnesium to produce one mole of magnesium chloride and one mole of hydrogen gas. Understanding this reaction highlights the principles of ionic compound formation and the behavior of metals in displacement reactions.

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

Answer: (C)

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

Answer: (C)

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

Answer: (B)

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.