Problem 111 - Chemistry The Molecular Nature of Matter

Question

In each of the following pairs, choose the metal that would most likely react more rapidly with a nonoxidizing acid such as HCl: (a) aluminum or iron, (b) zinc or nickel, and (c) cadmium or magnesium.

Step-by-Step Solution

Answer

The metals that would likely react more rapidly with HCl are (a) aluminum, (b) zinc, and (c) magnesium.

Step 1: Understand Activity Series

The activity series is a list of metals arranged in order of decreasing reactivity. In general, metals higher in the activity series will react more rapidly with acids than metals lower in the series. To answer the questions, refer to the activity series of metals.

Step 2: Identifying the More Reactive Metal in Pair (a)

Compare the position of aluminum (Al) and iron (Fe) on the activity series. Aluminum is above iron, meaning it is more reactive.

Step 3: Identifying the More Reactive Metal in Pair (b)

Compare the position of zinc (Zn) and nickel (Ni) on the activity series. Zinc is above nickel, meaning it is more reactive.

Step 4: Identifying the More Reactive Metal in Pair (c)

Compare the position of cadmium (Cd) and magnesium (Mg) on the activity series. Magnesium is above cadmium, meaning it is more reactive.

Key Concepts

Chemistry Education

Understanding the activity series of metals is essential in the field of chemistry education. By grasping this concept, students can predict and explain the outcome of reactions between metals and various substances, including acids. To make this easier, we often start with an activity series chart, a tool that ranks metals according to their tendency to react. Metals that are higher up in the series, like magnesium, are more likely to react than those lower down, like gold.

When educating students about the activity series, it is crucial to emphasize the practical applications, such as determining which metal to use in a specific chemical process or predicting the results of a reaction. Interactive experiments can help solidify these concepts, allowing students to witness the varying reactivity levels firsthand.

Metal Reactivity

The concept of metal reactivity is central to understanding how different metals interact with nonoxidizing acids like HCl. Reactivity refers to how easily a metal will undergo a chemical reaction, particularly with acids and oxygen.

A metal's position on the activity series dictates its reactivity; metals higher on the list will react more vigorously. For example, when aluminum (Al) is placed in HCl, it reacts faster and more intensely than iron (Fe). Practical advice for students is to always check the activity series when faced with questions about metal reactivity to avoid common misconceptions and predict the outcomes accurately.

Factors Influencing Reactivity

Several factors determine a metal's reactivity, such as electron configuration and ionization energy; knowing these can provide deeper insights into the why's of metal reactivity.

Nonoxidizing Acids

Nonoxidizing acids, like hydrochloric acid (HCl), are a class of acids that, as the name suggests, do not readily take part in oxidation reactions. This characteristic means they typically don't accept electrons during a reaction. Their primary reaction with metals is to release hydrogen gas and form a salt.

In the context of the activity series, the reaction with nonoxidizing acids serves as a good measure of a metal's reactivity. Metals higher on the activity series, such as magnesium (Mg), will react more enthusiastically with nonoxidizing acids. This understanding helps predict which metals can be safely used in environments where such acids are present and which are likely to corrode or react dangerously.