Problem 5 - Chemistry and Chemical Reactivity

Question

Balance the following equations and name each reactant and product: (a) \(\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+\mathrm{Mg}(\mathrm{s}) \longrightarrow \mathrm{MgO}(\mathrm{s})+\mathrm{Fe}(\mathrm{s})\) (b) \(\mathrm{AlCl}_{3}(\mathrm{s})+\mathrm{NaOH}(\mathrm{aq}) \longrightarrow \mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})+\mathrm{NaCl}(\mathrm{aq})\) (c) \(\mathrm{NaNO}_{3}(\mathrm{s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\ell) \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{s})+\mathrm{HNO}_{3}(\ell)\) (d) \(\mathrm{NiCO}_{3}(\mathrm{s})+\mathrm{HNO}_{3}(\mathrm{aq}) \longrightarrow\) \(\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)\)

Step-by-Step Solution

Answer

The balanced equations are: (a) \( \mathrm{Fe}_2\mathrm{O}_3 + 3\mathrm{Mg} \rightarrow 3\mathrm{MgO} + 2\mathrm{Fe} \), (b) \( \mathrm{AlCl}_3 + 3\mathrm{NaOH} \rightarrow \mathrm{Al(OH)}_3 + 3\mathrm{NaCl} \), (c) \( 2\mathrm{NaNO}_3 + \mathrm{H}_2\mathrm{SO}_4 \rightarrow \mathrm{Na}_2\mathrm{SO}_4 + 2\mathrm{HNO}_3 \), (d) \( \mathrm{NiCO}_3 + 2\mathrm{HNO}_3 \rightarrow \mathrm{Ni(NO}_3)_2 + \mathrm{CO}_2 + \mathrm{H}_2\mathrm{O} \).

Step 1: Write Original Equation (a)

Start with given unbalanced equation: \( \mathrm{Fe}_{2} \mathrm{O}_{3} (\mathrm{s}) + \mathrm{Mg} (\mathrm{s}) \longrightarrow \mathrm{MgO} (\mathrm{s}) + \mathrm{Fe} (\mathrm{s}) \).

Step 2: Name Reactants and Products (a)

- Reactants: Iron(III) oxide (\(\mathrm{Fe}_2\mathrm{O}_3\)) and Magnesium (\(\mathrm{Mg}\)).- Products: Magnesium oxide (\(\mathrm{MgO}\)) and Iron (\(\mathrm{Fe}\)).

Step 3: Balance Magnesium and Iron (a)

Match the number of Fe and Mg on both sides. Set the coefficients as follows: \( \mathrm{Fe}_{2} \mathrm{O}_{3} (\mathrm{s}) + 3\mathrm{Mg} (\mathrm{s}) \longrightarrow 3\mathrm{MgO} (\mathrm{s}) + 2\mathrm{Fe} (\mathrm{s}) \).

Step 4: Write Original Equation (b)

Start with the unbalanced equation: \( \mathrm{AlCl}_{3} (\mathrm{s}) + \mathrm{NaOH} (\mathrm{aq}) \longrightarrow \mathrm{Al} (\mathrm{OH})_{3} (\mathrm{s}) + \mathrm{NaCl} (\mathrm{aq}) \).

Step 5: Name Reactants and Products (b)

- Reactants: Aluminum chloride (\(\mathrm{AlCl}_3\)) and Sodium hydroxide (\(\mathrm{NaOH}\)).- Products: Aluminum hydroxide (\(\mathrm{Al(OH)}_3\)) and Sodium chloride (\(\mathrm{NaCl}\)).

Step 6: Balance the Equation (b)

To balance the equation, adjust the coefficients: \( \mathrm{AlCl}_{3} (\mathrm{s}) + 3\mathrm{NaOH} (\mathrm{aq}) \longrightarrow \mathrm{Al} (\mathrm{OH})_{3} (\mathrm{s}) + 3\mathrm{NaCl} (\mathrm{aq}) \).

Step 7: Write Original Equation (c)

Begin with the unbalanced equation: \( \mathrm{NaNO}_{3} (\mathrm{s}) + \mathrm{H}_{2} \mathrm{SO}_{4} (\ell) \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4} (\mathrm{s}) + \mathrm{HNO}_{3} (\ell) \).

Step 8: Name Reactants and Products (c)

- Reactants: Sodium nitrate (\(\mathrm{NaNO}_3\)) and Sulfuric acid (\(\mathrm{H}_2\mathrm{SO}_4\)).- Products: Sodium sulfate (\(\mathrm{Na}_2\mathrm{SO}_4\)) and Nitric acid (\(\mathrm{HNO}_3\)).

Step 9: Balance Sodium and Nitrate Ions (c)

Balance the equation by setting coefficients: \( 2\mathrm{NaNO}_{3} (\mathrm{s}) + \mathrm{H}_{2} \mathrm{SO}_{4} (\ell) \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4} (\mathrm{s}) + 2\mathrm{HNO}_{3} (\ell) \).

Step 10: Write Original Equation (d)

Start with given unbalanced equation: \( \mathrm{NiCO}_{3} (\mathrm{s}) + \mathrm{HNO}_{3} (\mathrm{aq}) \longrightarrow \mathrm{Ni} (\mathrm{NO}_{3})_{2} (\mathrm{aq}) + \mathrm{CO}_{2} (\mathrm{g}) + \mathrm{H}_{2} \mathrm{O} (\ell) \).

Step 11: Name Reactants and Products (d)

- Reactants: Nickel(II) carbonate (\(\mathrm{NiCO}_3\)) and Nitric acid (\(\mathrm{HNO}_3\)).- Products: Nickel(II) nitrate (\(\mathrm{Ni(NO}_3)_2\)), Carbon dioxide (\(\mathrm{CO}_2\)), and Water (\(\mathrm{H}_2\mathrm{O}\)).

Step 12: Balance Nickel, Carbonate, and Nitrate Ions (d)

Balance the equation by adjusting the coefficients: \( \mathrm{NiCO}_{3} (\mathrm{s}) + 2\mathrm{HNO}_{3} (\mathrm{aq}) \longrightarrow \mathrm{Ni} (\mathrm{NO}_{3})_{2} (\mathrm{aq}) + \mathrm{CO}_{2} (\mathrm{g}) + \mathrm{H}_{2} \mathrm{O} (\ell) \).

Key Concepts

Reactants and Products

In any chemical equation, it's crucial to identify the reactants and products to understand what substances start the reaction and what new substances are formed. Reactants are the starting materials in a chemical reaction, and they undergo a transformation. Products, meanwhile, are the substances that result from this change.

For example, in the reaction \(\mathrm{Fe}_{2}\mathrm{O}_{3} + \mathrm{Mg} \rightarrow \mathrm{MgO} + \mathrm{Fe}\), the reactants are iron(III) oxide \(\mathrm{Fe}_{2}\mathrm{O}_{3}\) and magnesium \(\mathrm{Mg}\), while the products are magnesium oxide \(\mathrm{MgO}\) and iron \(\mathrm{Fe}\). Identifying each reactant and product is a foundational step in understanding the changes occurring during the reaction.

Chemical Nomenclature

Chemical nomenclature is a system of naming substances. It provides a standardized way to refer to chemical compounds and helps avoid confusion.

Each compound has a specific name that provides information about its structure and composition. For example, \(\mathrm{Fe}_{2}\mathrm{O}_{3}\) is named iron(III) oxide. The Roman numeral "III" indicates the oxidation state of iron in the compound. Similarly, \(\mathrm{NaCl}\) is known as sodium chloride, where the first part of the name indicates the metallic element sodium, and the second part, chloride, indicates the presence of chlorine ions.

This system is used globally and allows scientists from different regions to communicate more effectively. Understanding chemical nomenclature is essential for identifying reactants and products and for writing chemical equations accurately.

Stoichiometry

Stoichiometry is the area of chemistry that relates to the quantitative analysis of reactants and products in a chemical reaction. It involves using balanced chemical equations to determine the amount of either reactants or products.

In a balanced equation, the number of atoms for each element is the same on both sides. This balance is important because it reflects the conservation of mass. For example, consider the equation \(\mathrm{Fe}_{2}\mathrm{O}_{3} + 3\mathrm{Mg} \rightarrow 3\mathrm{MgO} + 2\mathrm{Fe}\). Here, the stoichiometry tells us that two moles of iron(III) oxide react with three moles of magnesium to yield three moles of magnesium oxide and two moles of iron.

Stoichiometry is crucial for calculating reactant quantities necessary to produce a desired amount of product, and it helps in predicting the yields of reactions.

Chemical Reactions

Chemical reactions are processes in which substances, known as reactants, are transformed into different substances, called products. They involve the breaking of bonds in reactants and the forming of new bonds to create products.

Chemical reactions are diverse and can be classified into different types, such as:

• Combination reactions where two or more substances combine to form a single product.
• Decomposition reactions where a single compound breaks down into two or more simpler substances.
• Displacement reactions where an element in a compound is replaced by another element.

Understanding the type of reaction can provide important insights into how substances interact and transform at the molecular level.

Equation Balancing Steps

Balancing equations is a fundamental skill in chemistry that ensures the principle of mass conservation is obeyed. In a chemical reaction, atoms are neither created nor destroyed, so the same number of each type must appear on both sides of the equation.

To balance a chemical equation, you can follow these general steps:

• Write the unbalanced equation with correct chemical formulas.
• Identify and list the number of atoms of each element in both reactants and products.
• Add coefficients in front of compounds to balance the number of atoms for each element on both sides.
• Adjust coefficients as needed until the equation is balanced.
• Check your work to ensure all elements are balanced and verify all coefficients are in the smallest possible ratio.

Balancing chemical equations is essential for proper stoichiometry calculations, and practice makes this process more intuitive over time.