Problem 6 - Chemistry and Chemical Reactivity

Question

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

Step-by-Step Solution

Answer

(a) ZnSO₄ and Cu; (b) ZnCl₂ and H₂; (c) FeCl₃; (d) V₂O₅, all balanced.

Step 1: Identify the Type of Reaction

For each reaction, determine what type of chemical reaction it involves, such as synthesis, decomposition, single replacement, or double replacement. This helps predict the products.

Step 2: Predict the Products - (a)

For reaction (a) with copper(II) sulfate and zinc, identify that this is a single replacement reaction where zinc displaces copper. The products will be zinc sulfate (\(\mathrm{ZnSO_4}\)) and copper metal (\(\mathrm{Cu}\)).

Step 3: Predict the Products - (b)

For reaction (b) with zinc and hydrochloric acid, identify that this is also a single replacement reaction. Zinc will displace hydrogen, leading to the formation of zinc chloride (\(\mathrm{ZnCl_2}\)) and hydrogen gas (\(\mathrm{H_2}\)).

Step 4: Predict the Products - (c)

For reaction (c) with iron and chlorine, recognize that this is a synthesis reaction forming iron(III) chloride (\(\mathrm{FeCl_3}\)).

Step 5: Predict the Products - (d)

For reaction (d) with vanadium and oxygen, recognize that this is another synthesis reaction forming vanadium(V) oxide (\(\mathrm{V_2O_5}\)).

Step 6: Balance the Equation - (a)

For the reaction of zinc with copper(II) sulfate: \[ \mathrm{CuSO_4(aq) + Zn(s) \rightarrow ZnSO_4(aq) + Cu(s)} \] Equation is balanced as each element has an equal count on both sides.

Step 7: Balance the Equation - (b)

For the reaction of zinc with hydrochloric acid: \[ \mathrm{Zn(s) + 2HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)} \] Balance the equation by placing a coefficient of 2 in front of \(\mathrm{HCl}\).

Step 8: Balance the Equation - (c)

For the reaction of iron with chlorine: \[ 2\mathrm{Fe(s) + 3Cl_2(g) \rightarrow 2FeCl_3(s)} \] The equation is balanced by placing coefficients to equalize the number of each type of atom on both sides.

Step 9: Balance the Equation - (d)

For the reaction of vanadium with oxygen: \[ 4\mathrm{V(s) + 5O_2(g) \rightarrow 2V_2O_5(s)} \] Coefficients are adjusted to balance the number of vanadium and oxygen atoms.

Key Concepts

Single Replacement Reaction

Single replacement reactions, also known as single displacement reactions, occur when an element reacts with a compound and replaces one of the elements in that compound. Think of it as a dance where one partner (a single element) cuts in and replaces another partner in the compound. Here's a quick breakdown of what happens:

• One element is typically a metal, and the compound is often ionic.
• The more reactive metal will replace the less reactive metal in the compound.

For example, in the reaction between copper(II) sulfate (\(\mathrm{CuSO_4}\)) and zinc (\(\mathrm{Zn}\)), zinc displaces copper because it is more reactive. This results in the formation of zinc sulfate (\(\mathrm{ZnSO_4}\)) and copper metal (\(\mathrm{Cu}\)).
Similarly, zinc replacing hydrogen in hydrochloric acid (\(\mathrm{HCl}\)) forms zinc chloride (\(\mathrm{ZnCl_2}\)) and hydrogen gas (\(\mathrm{H_2}\)). Understanding the activity series of metals can help predict if and when such a replacement can occur in these reactions.

Synthesis Reaction

In a synthesis reaction, multiple reactants combine to form a single product. This is like building a new structure from various raw materials. It's also known as a combination reaction. Here are some essential points about synthesis reactions:

• They usually involve elements, but can also involve compounds.
• Involves exothermic reactions, meaning they release energy.

A great example is the reaction between iron and chlorine gas, forming iron(III) chloride (\(\mathrm{FeCl_3}\)). The equation starts with multiple atoms, \(2\mathrm{Fe}\) and \(3\mathrm{Cl_2}\), and synthesizes into \(2\mathrm{FeCl_3}\).
Vanadium reacting with oxygen forms vanadium(V) oxide (\(\mathrm{V_2O_5}\)), another perfect example where elements join forces to create a compound. Identifying synthesis reactions in chemistry can help predict the outcomes and understand how new substances are formed from simpler reactants.

Predicting Products

Predicting the products of a chemical reaction is a fundamental skill in chemistry. Here are some tips to master this skill:

• First, identify the type of reaction, whether it's single replacement, synthesis, or another type. Each type has characteristic products.
• Use the chemical reactivity series for single replacement reactions to predict which elements are capable of replacing others in a compound.
• For synthesis reactions, think about how different elements and compounds naturally come together to form stable products.

When examining copper(II) sulfate reacting with zinc, predicting zinc sulfate and copper as products is easier when recognizing the single replacement pattern.
Similarly, knowing zinc and HCl will produce hydrogen gas and zinc chloride helps illustrate product prediction in single displacement contexts. Making connections between reactants and products simplifies and clarifies chemical reactions.

Balancing Chemical Equations

Balancing chemical equations is crucial for expressing a reaction accurately. Every balanced equation respects the law of conservation of mass, meaning atoms are neither created nor destroyed. To balance equations, follow these steps:

• Write down the number of each atom on both sides of the equation.
• Use coefficients to equalize and balance each type of atom.

Take the reaction between \(\mathrm{Zn}\) and \(\mathrm{HCl}\), resulting in \(\mathrm{ZnCl_2}\) and \(\mathrm{H_2}\). By using a coefficient of 2 in front of \(\mathrm{HCl}\), the equation balances, \(\mathrm{Zn(s) + 2HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)}\).
For the synthesis of \(\mathrm{FeCl_3}\), balancing the equation \(2\mathrm{Fe(s) + 3Cl_2(g) \rightarrow 2FeCl_3(s)}\) ensures both sides have equal \(\mathrm{Fe}\) and \(\mathrm{Cl}\) atoms. This systematic approach guarantees understanding of reactant transformation to products, essential for laboratory work and theoretical predictions.