Problem 6 - Chemistry and Chemical Reactivity

Question

Identify the products of each reaction and balance the equation. (a) \(\operatorname{CuSO}_{4}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s}) \longrightarrow\) (b) \(\mathrm{Zn}(\mathrm{s})+\mathrm{HCl}(\mathrm{aq}) \longrightarrow\) (c) \(\mathrm{Fe}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{g}) \longrightarrow\) (d) \(V(s)+O_{2}(g) \longrightarrow\)

Step-by-Step Solution

Answer

(a) ZnSO₄(aq) + Cu(s), balanced as Zn + CuSO₄ → ZnSO₄ + Cu. (b) ZnCl₂(aq) + H₂(g), balanced as Zn + 2HCl → ZnCl₂ + H₂. (c) FeCl₃, balanced as 2Fe + 3Cl₂ → 2FeCl₃. (d) V₂O₅, balanced as 4V + 5O₂ → 2V₂O₅.

Step 1: Identify the Reaction Type

Recognize each reaction. For (a), it is a single replacement reaction where Zn displaces Cu from CuSO₄. For (b), it is a single replacement reaction where Zn displaces H from HCl. For (c), iron reacts with chlorine, which is a synthesis reaction to form iron(III) chloride. For (d), vanadium reacts with oxygen, which is a synthesis reaction to form vanadium pentoxide.

Step 2: Predict the Products

For reaction (a), Zn displaces Cu leading to products ZnSO₄(aq) and Cu(s). For (b), Zn displaces H leading to ZnCl₂(aq) and H₂(g). For (c), Fe reacts with Cl₂ to form FeCl₃. For (d), V reacts with O₂ to form V₂O₅.

Step 3: Write the Unbalanced Equations

(a) Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s). (b) Zn(s) + HCl(aq) → ZnCl₂(aq) + H₂(g). (c) Fe(s) + Cl₂(g) → FeCl₃(s). (d) V(s) + O₂(g) → V₂O₅(s).

Step 4: Balance the Equations

(a) The balanced equation is Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s). (b) Balance H and Cl: Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g). (c) Balance Fe and Cl: 2Fe(s) + 3Cl₂(g) → 2FeCl₃(s). (d) Balance V and O: 4V(s) + 5O₂(g) → 2V₂O₅(s).

Key Concepts

Single Replacement Reaction

In a single replacement reaction, one element replaces another element in a compound. This type of reaction is basic yet vital in the study of chemical reactions. It is also known as a single displacement reaction.
Imagine you go to a dance with your partner - if your partner decides to dance with someone else, that's akin to a single replacement (or displacement) reaction.

• In the case of CuSO₄(aq) and Zn(s), zinc replaces copper, forming ZnSO₄(aq) and Cu(s).
• Similarly, in Zn(s) + HCl(aq), zinc replaces the hydrogen, producing ZnCl₂(aq) and H₂(g).

Knowing which elements can be replaced is key. Metals can typically replace other metals, and activity series can help predict whether a metal will replace another in a compound.

Synthesis Reaction

A synthesis reaction occurs when two or more simple substances combine to form a more complex substance. This is a building-up reaction, where you create something new from simpler components.
Consider how letters combine to form words - this is similar to a synthesis reaction. Individual letters mean something first, but they convey much more when arranged as words.

• In the reaction between iron (Fe) and chlorine (Cl₂), you create iron(III) chloride (FeCl₃).
• When vanadium (V) reacts with oxygen (O₂), vanadium pentoxide (V₂O₅) forms.

These processes are fundamental in chemistry, allowing us to understand how complex materials come into existence from simpler substances.

Balancing Chemical Equations

Balancing chemical equations ensures that the same number of each element is present on both sides of the equation, reflecting the conservation of mass. In a balanced equation, atoms are not created or destroyed, rather rearranged.
Think of it like balancing a teeter-totter - equal weight on both sides is crucial for equilibrium.
Here are a few steps to balance an equation:

• First, write the unbalanced equation with correct chemical formulas.
• Add coefficients to compounds to balance each type of atom across reactants and products.
• Adjust coefficients as required, starting with the element that appears in the least number of compounds.
• Make sure all coefficients are in the smallest whole number ratios.

This systematic method ensures the balanced equation reflects the actual chemical process happening.

Chemical Equations

Chemical equations represent chemical reactions using symbols and formulas. They are powerful tools for describing reactions in a concise way, capturing the essence of what takes place during a reaction.
A chemical equation contains reactants and products, with an arrow showing the direction of the reaction.
Understanding chemical equations involves knowing:

• Reactants: Substances that start a reaction.
• Products: Substances that are produced by the reaction.
• Symbols: States of matter such as (s), (l), (g), (aq) indicate solid, liquid, gas, or aqueous solutions.

These elements come together in equations to succinctly convey the important details of a chemical reaction, helping chemists and students alike visualize and predict the outcomes of reactions.