3.2.4. How do Metals react with Solutions of other Metal Salts?

n Take a clean wire of copper and an iron nail. n Put the copper wire in a solution of iron sulphate and the iron nail in a solution of copper sulphate taken in test tubes (Fig. 3.4). n Record your observations after 20 minutes. n In which test tube did you find that a reaction has occurred? n On what basis can you say that a reaction has actually taken place? n Can you correlate your observations for the Activities 3.9, 3.10 and 3.11? n Write a balanced chemical equation for the reaction that has taken place. n Name the type of reaction.

This chunk describes an activity involving displacement reactions between metals and their salt solutions. In this experiment, students will examine how copper and iron react when placed in solutions of one another’s salts. By observing changes in the appearance of the solutions and the metals, students can determine if a reaction occurred. If a metal changes color or if a solid (precipitate) forms, these indicate a reaction. A balanced chemical equation must then be written to describe the reaction quantitatively, identifying the products formed.

Think of this reaction like a game of musical chairs. If a more popular kid (a more reactive metal) comes into the game, they can take the chair (displace the other metal) from the less popular kid. So, in this case, if copper can 'take' the position of iron in its salt solution, it indicates that copper is less reactive compared to iron.

Reactive metals can displace less reactive metals from their compounds in solution or molten form. We have seen in the previous sections that all metals are not equally reactive. We checked the reactivity of various metals with oxygen, water and acids. But all metals do not react with these reagents. So we were not able to put all the metal samples we had collected in decreasing order of their reactivity. Displacement reactions studied in Chapter 1 give better evidence about the reactivity of metals. It is simple and easy: if metal A displaces metal B from its solution, it is more reactive than B. Reaction of metals with salt solutions: Metal A + Salt solution of B → Salt solution of A + Metal B.

This chunk explains the concept of displacement reactions in metals. It notes that reactive metals will displace less reactive metals from their salt solutions. The reactivity series provides a guide on how to predict which metals will displace others. If a metal in a reaction can successfully replace another from its solution, it proves that it is more reactive than the metal being replaced.

Imagine a classroom where a popular student can easily take a place next to the teacher (the more reactive metal can displace the less reactive one). Similarly, in a running race, if competitor A can outpace competitor B, they are faster (more reactive) – just like in metals, if A can displace B from a salt solution, A is considered more reactive.

Which metal, copper or iron, is more reactive according to your observations in Activity 3.12?

This question encourages students to analyze their previous experimental results from the activities done. By observing which metal displaced the other, students can conclude which is more reactive. If iron displaces copper from the copper sulfate solution, iron is more reactive. Conversely, if copper did not displace iron from the iron sulfate solution, this helps cement understanding of the pattern of reactivity.

Consider a story where a small dog challenges a larger dog to a bark-off. If the larger dog backs down, the smaller dog is deemed 'braver,' just like the reactive metal that takes over a salt solution. This experiment helps students associate real-life decision-making with the concept of reactivity.

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