Question

A common experiment to determine the relative reactivity of metallic elements is to place a pure sample of one metal into an aqueous solution of a compound of another metallic element. If the pure metal you are adding is more reactive than the metallic element in the compound, then the pure metal will replace the metallic element in the compound. For example, if you place a piece of pure zinc metal into a solution of copper(II) sulfate, the zinc will slowly dissolve to produce zinc sulfate solution, and the copper(II) ion of the copper(II) sulfate will be converted to metallic copper. Write the unbalanced equation for this process.

Short answer

The unbalanced equation for the reaction between pure zinc metal and copper(II) sulfate solution is: Zn + CuSO4 → ZnSO4 + Cu

Step-by-step solution

1. Identify the reactants and products

In this experiment, the reactants are pure zinc metal (Zn) and copper(II) sulfate (CuSO4). The products are zinc sulfate (ZnSO4) and metallic copper (Cu).

2. Write the unbalanced equation

Write the chemical symbols of the reactants on the left side of the equation and the products on the right side. Leave space between the reactants and products for the coefficients that balance the equation. Zn + CuSO4 → ZnSO4 + Cu Now we have the unbalanced equation for the reaction between pure zinc metal and copper(II) sulfate solution.

Key concepts

Reactivity of Metals

Understanding the reactivity of metals is essential when studying chemical reactions, especially when referring to single displacement reactions. Reactivity refers to the tendency of a metal to lose electrons and form positive ions, known as cations. Metals vary widely in their reactivity, with some willing to react at even a slight chance, while others are more reluctant.

In a single displacement reaction, a more reactive metal can displace a less reactive metal from its compound. This creates a hierarchy among metals where some are better at displacing others from their compounds. This hierarchy is represented in a reactivity series where metals like lithium and potassium are at the top, meaning they're highly reactive, and metals like gold and platinum are at the bottom, suggesting they are least reactive.

When we observe a metal undergoing replacement, as in the textbook example of zinc replacing copper in a copper(II) sulfate solution, we can infer from the reactivity series that zinc must be more reactive than copper. Indeed, zinc is willing to oxidize (lose electrons) more readily than copper, pushing the copper ions out of solution and causing them to gain electrons to form solid copper on the metal's surface.

Chemical Equations

Chemical equations are more than just a string of letters and numbers; they're a concise way to represent chemical reactions. They consist of reactants (substances at the beginning of a reaction) and products (substances formed by the reaction), with an arrow indicating the direction of the reaction. Reactants are placed to the left of the arrow, while products are shown to the right.

In the example provided, the reactants are zinc (Zn) and copper(II) sulfate (CuSO4), and the products are zinc sulfate (ZnSO4) and copper (Cu). The unbalanced chemical equation is written as:
Zn + CuSO4 → ZnSO4 + Cu

Each chemical symbol and formula represents a different element or compound, with its unique properties and role in the reaction. The arrangement of these symbols in the equation provides information about the proportions in which substances react and the products they form.

Balancing Chemical Equations

Balancing chemical equations is a critical skill in chemistry, essential for honoring the law of conservation of mass that dictates that atoms are neither created nor destroyed in a chemical reaction. To balance an equation, we must ensure that there are equal numbers of each type of atom on both the reactant and product sides of the equation.

Let's take the provided chemical equation as an example:
Zn + CuSO4 → ZnSO4 + Cu

Initially, it might look balanced, but upon closer examination, we see that it's not. Although there is one zinc atom on both sides, there's only one copper atom on the reactants' side and one on the products' side. However, sulfur and oxygen need to be counted too. The sulfate group (SO4) has one sulfur and four oxygens, so we must ensure there's the same count on both sides of the equation. In this case, our initial equation is already balanced in terms of sulfur and oxygen, a coincidental factor of the specific reaction at hand.

However, it is worth noting that more complex reactions may require adding coefficients - small whole numbers placed in front of compounds in a reaction to balance the equation. These coefficients multiply the number of atoms of each element in the compound or element they precede to achieve balance. It's like solving a puzzle where the pieces are the atoms, and the picture is the balanced equation that obeys the laws of nature.