Problem 81 - Chemistry: The Central Science

Question

Write a balanced equation for the reaction that occurs in each of the following cases: (a) Ozone decomposes to dioxygen. (b) Xenon reacts with fluorine. (Write three different equations.) (c) Sulfur reacts with hydrogen gas. (d) Fluorine reacts with water.

Step-by-Step Solution

Answer

The balanced chemical equations for the reactions are: (a) \(2O_3 → 3O_2\) (b) 1) \(Xe + F_2 → XeF_2\), 2) \(Xe + 2F_2 → XeF_4\), 3) \(Xe + 3F_2 → XeF_6\) (c) \(S + 2H_2 → 2H_2S\) (d) \(F_2 + 2H_2O → 4HF + O_2\)

Step 1: a) Ozone decomposes to dioxygen

In this reaction, ozone (O3) decomposes into dioxygen (O2). Write the unbalanced equation first: O3 → O2 Now balance the equation by adding the coefficients to ensure that the number of oxygen atoms is the same on both sides of the equation: 2O3 → 3O2 The balanced chemical equation is: \[2O_3 → 3O_2\]

Step 2: b) Xenon reacts with fluorine (Write three different equations)

Here, xenon (Xe) reacts with fluorine (F2) to form three possible xenon fluorides: XeF2, XeF4, and XeF6. Write the unbalanced equations: 1) Xe + F2 → XeF2 2) Xe + F2 → XeF4 3) Xe + F2 → XeF6 Now balance the equations by adding coefficients to ensure the number of xenon and fluorine atoms are equal on both sides of the equation: 1) Xe + F2 → XeF2 (already balanced) 2) Xe + 2F2 → XeF4 3) Xe + 3F2 → XeF6 The balanced chemical equations are: 1) \(Xe + F_2 → XeF_2\) 2) \(Xe + 2F_2 → XeF_4\) 3) \(Xe + 3F_2 → XeF_6\)

Step 3: c) Sulfur reacts with hydrogen gas

In this reaction, sulfur (S) reacts with hydrogen gas (H2) to form hydrogen sulfide (H2S). Write the unbalanced equation: S + H2 → H2S Now balance the equation by adding coefficients to ensure that the number of sulfur and hydrogen atoms is equal on both sides of the equation: S + 2H2 → 2H2S The balanced chemical equation is: \[S + 2H_2 → 2H_2S\]

Step 4: d) Fluorine reacts with water

In this reaction, fluorine (F2) reacts with water (H2O) to form hydrogen fluoride (HF) and oxygen gas (O2). Write the unbalanced equation: F2 + H2O → HF + O2 Now balance the equation by adding coefficients to ensure that the number of fluorine, hydrogen, and oxygen atoms are equal on both sides of the equation: F2 + 2H2O → 4HF + O2 The balanced chemical equation is: \[F_2 + 2H_2O → 4HF + O_2\]

Key Concepts

Balancing Equations

Balancing chemical equations is a vital skill in chemistry that ensures atoms are neither created nor destroyed, adhering to the law of conservation of mass. To balance an equation, follow these steps:

• Write the skeleton equation with the reactants and products, including correct formulas.
• Count the number of each type of atom on both sides of the arrow.
• Add coefficients to balance the atoms, starting with the most complex molecule.
• Ensure all coefficients are in the simplest whole number ratio.

For example, when ozone decomposes into dioxygen, the unbalanced equation is \(O_3 \rightarrow O_2\). Balancing involves adjusting coefficients:

• Write the decomposition equation as \(2O_3 \rightarrow 3O_2\).
• Check to ensure both sides have six oxygen atoms, confirming the equation is balanced.

Practicing this method helps in mastering the art of equation balancing.

Types of Reactions

Chemical reactions can be classified into various types based on their reactants and products. Knowing these types helps in predicting the outcomes of reactions and understanding their processes.

For example, the reaction of xenon with fluorine can produce three types of xenon fluorides:

• Synthesis Reactions: Multiple reactants combine to form a single product. For instance, \(Xe + F_2 \rightarrow XeF_2\).
• Combination Reactions: A type of synthesis where two elements or simple compounds react. Example: \(Xe + 2F_2 \rightarrow XeF_4\).
• Variation Reactions: Reactants can produce different products under varied conditions, like \(Xe + 3F_2 \rightarrow XeF_6\).

Other reaction types include decomposition (breaking down of compounds) and displacement (exchange of components), useful for understanding chemical behavior and applications.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves the use of balanced equations to determine the proportions of substances involved.

Here are key steps to use stoichiometry:

• Start with a balanced chemical equation.
• Identify the known and unknown quantities: moles, mass, or volume.
• Use molar ratios derived from coefficients in the balanced equation to relate amounts.
• Convert between moles and other units when necessary using molar masses.

Consider fluorine reacting with water:

• The balanced equation is \(F_2 + 2H_2O \rightarrow 4HF + O_2\).
• This tells us for every 1 mole of \(F_2\), 2 moles of \(H_2O\) react to produce 4 moles of \(HF\) and 1 mole of \(O_2\).

Stoichiometry ensures accurate calculations in real-world applications, such as determining the amounts of materials needed in a reaction.