Question

Complete and balance the following equations. (a) \(\mathrm{KClO}_{3}+\) heat \(\rightarrow\) (b) \(\mathrm{H}_{2} \mathrm{S}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow\) (c) \(\mathrm{Na}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow\) (d) \(\mathrm{P}_{4}(\mathrm{s})+\mathrm{KOH}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow\) (e) \(\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{s})+\) heat \(\rightarrow\) (f) \(\operatorname{In}(\mathrm{s})+\mathrm{Br}_{2}(\ell) \rightarrow\) (g) \(\operatorname{SnCl}_{4}(\ell)+\mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow\)

Short answer

Equations are balanced: a (2 KClO₃ → 2 KCl + 3 O₂), b (2 H₂S + 3 O₂ → 2 SO₂ + 2 H₂O), c (4 Na + O₂ → 2 Na₂O), d (P₄ + 4 KOH + 2 H₂O → 2 PH₃ + 2 KH₂PO₂), e (NH₄NO₃ → N₂O + 2 H₂O), f (2 In + 3 Br₂ → 2 InBr₃), g (SnCl₄ + 2 H₂O → SnO₂ + 4 HCl).

Step-by-step solution

Understand the Reactants and Products

For each chemical equation given, identify the reactants, and determine the potential products. In many cases, common decomposition or combination reactions can guide identification.

Write the Possible Chemical Reactions

Based on common reaction types, write the possible unbalanced chemical equations for each problem: (a) KClO₃ decomposes into KCl and O₂. (b) H₂S reacts with O₂ to form SO₂ and H₂O. (c) Na reacts with O₂ to form Na₂O. (d) P₄ reacts with KOH and H₂O to form PH₃ and KH₂PO₂. (e) NH₄NO₃ decomposes into N₂O and H₂O. (f) In reacts with Br₂ to form InBr₃. (g) SnCl₄ reacts with H₂O to form SnO₂ and HCl.

Balance Each Chemical Equation

Adjust the coefficients to balance the atoms of each element on both sides of each chemical equation: (a) 2 KClO₃ → 2 KCl + 3 O₂ (b) 2 H₂S + 3 O₂ → 2 SO₂ + 2 H₂O (c) 4 Na + O₂ → 2 Na₂O (d) P₄ + 4 KOH + 2 H₂O → 2 PH₃ + 2 KH₂PO₂ (e) NH₄NO₃ → N₂O + 2 H₂O (f) 2 In + 3 Br₂ → 2 InBr₃ (g) SnCl₄ + 2 H₂O → SnO₂ + 4 HCl.

Verify and Finalize the Balancing

Check that each equation has equal numbers of each type of atom on both sides, ensuring the equations are balanced: (a) KClO₃ decomposes to KCl and O₂. (b) H₂S + O₂ forms SO₂ and H₂O. (c) Na + O₂ forms Na₂O. (d) P₄ + KOH + H₂O forms PH₃ and KH₂PO₂. (e) NH₄NO₃ decomposes to N₂O and H₂O. (f) In + Br₂ forms InBr₃. (g) SnCl₄ + H₂O forms SnO₂ and HCl.

Key concepts

Reactants and Products

In a chemical reaction, reactants are the substances that undergo a transformation, while products are the new substances formed. Reactants are always written on the left side of a chemical equation, and products are on the right. For example, in the reaction where potassium chlorate (\(\mathrm{KClO}_{3}\)) decomposes with heat, \(\mathrm{KClO}_{3}\) is the reactant, and the products are potassium chloride (\(\mathrm{KCl}\)) and oxygen gas (\(\mathrm{O}_{2}\)).
Identifying reactants and products is crucial for writing chemical equations correctly. It allows chemists to understand what substances are consumed and what new substances are produced in a reaction. Moreover, recognizing the products can help predict the type of reaction occurring, such as combustion, synthesis, or decomposition, because the products often hint at these distinctive processes.
In every correctly balanced chemical equation, the mass and the number of atoms of each element are the same for both reactants and products, affirming the Law of Conservation of Mass. This foundational concept is important for anyone learning to write and balance chemical equations.

Decomposition Reactions

Decomposition reactions occur when a single compound breaks down into two or more simpler substances. This type of reaction generally requires an input of energy, such as heat, light, or electricity. For instance, when heating potassium chlorate (\(\mathrm{KClO}_{3}\)), it decomposes into potassium chloride (\(\mathrm{KCl}\)) and oxygen gas (\(\mathrm{O}_{2}\)).
Decomposition reactions can be identified by their general formula: \[\text{AB} \rightarrow \text{A} + \text{B}\]
This formula represents the breaking apart of compound "AB" into simpler products A and B. Notable examples include the decomposition of hydrogen peroxide into water and oxygen, and the electrolysis of water into hydrogen and oxygen.
Such reactions are vital in industrial processes. For example, the production of oxygen in laboratories often involves the decomposition of potassium chlorate. Understanding how decomposition works helps in manipulating chemical reactions for desired outcomes in both experimental and industrial applications.

Combination Reactions

Combination reactions, also called synthesis reactions, occur when two or more substances combine to form a more complex product. These reactions are characterized by the formation of a new compound from simpler reactants. For example, sodium (\(\mathrm{Na}\)) reacting with oxygen (\(\mathrm{O}_{2}\)) to form sodium oxide (\(\mathrm{Na}_{2}\mathrm{O}\)).
The general form of combination reactions is: \[\text{A} + \text{B} \rightarrow \text{AB}\]
This formula indicates the joining of substances A and B to form AB. A simple instance is the formation of water from hydrogen and oxygen. Combination reactions are prevalent in various natural and industrial processes, such as the rusting of iron or the synthesis of ammonia.
Combination reactions are essential in producing compounds necessary for daily life and in manufacturing industries. They illustrate how simple substances combine to create products with different properties, showcasing the diversity achievable through chemical reactions.

Chemical Equation Balancing Steps

Balancing chemical equations ensures that the same number of each type of atom appears on both sides of the equation, reflecting the Law of Conservation of Mass. Here is a step-by-step guide to balancing chemical equations:

• Write the unbalanced equation with correct chemical formulas for all reactants and products.
• Count the number of atoms for each element on both sides of the equation.
• Start by balancing elements that appear in only one reactant and one product.
• Use coefficients to balance elements. Adjust them in front of compounds or molecules.
• Continue to balance each element, one at a time, preferably moving to elements that appear more frequently in the equation.
• Check the balance by recounting all atoms of each element to ensure equal numbers on both sides.

For example, in the decomposition of \(\mathrm{KClO}_{3}\), balance by placing coefficients to have an equal count of potassium, chlorine, and oxygen atoms on both sides. The balanced equation is:\[2\;\mathrm{KClO}_3 \rightarrow 2\;\mathrm{KCl} + 3\;\mathrm{O}_2\]
Balancing equations is essential for accurately depicting chemical reactions, allowing predictions of product amounts and informing experimental conditions.