Problem 41 - Introductory Chemistry Atoms First

Question

Under the proper conditions, hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}(l)\), can be converted to water and oxygen gas. Write a balanced equation for this reaction and assign it a reaction type.

Step-by-Step Solution

Answer

The balanced equation for the conversion of hydrogen peroxide to water and oxygen gas is: \(2\mathrm{H}_{2}\mathrm{O}_{2}(l) \rightarrow 2\mathrm{H}_{2}\mathrm{O}(l) + \mathrm{O}_{2}(g)\). This is a decomposition reaction, as a single reactant breaks down into simpler products.

Step 1: Identify Reactants and Products#line_break#

The reactants for this reaction are given in the problem, hydrogen peroxide (H2O2). The products are mentioned as water (H2O) and oxygen gas (O2). Reactants: H2O2 Products: H2O and O2

Step 2: Write the Unbalanced Chemical Equation#line_break#

Now that we have identified the reactants and products, we can write the unbalanced chemical equation: H2O2 (l) → H2O (l) + O2 (g)

Step 3: Balance the Chemical Equation#line_break#

In order for the equation to be balanced, the number of atoms for each element must be the same on both the reactant and product sides of the equation. Unbalanced: H2O2 (l) → H2O (l) + O2 (g) Balanced: 2H2O2 (l) → 2H2O (l) + O2 (g) The balanced equation has two molecules of hydrogen peroxide converting to two molecules of water and one molecule of oxygen gas.

Step 4: Determine the Type of Reaction#line_break#

The balanced chemical equation is: 2H2O2 (l) → 2H2O (l) + O2 (g) This is a decomposition reaction because a single reactant (H2O2) breaks down into simpler products (H2O and O2).

Key Concepts

Chemical Reaction Types

In chemistry, reactions are classified based on how the reactants change to form the products. The major types include synthesis, decomposition, single replacement, double replacement, and combustion reactions.

During a synthesis reaction, multiple reactants combine to form a single product, exemplified by A + B → AB. In contrast, a single substance breaks down into two or more substances during a decomposition reaction, such as AB → A + B. Single replacement reactions involve an element reacting with a compound, displacing another element, shown as A + BC → AC + B. Double replacement reactions occur between ions in two compounds that switch places, forming two new compounds, as in AB + CD → AD + CB. Finally, combustion reactions are characterized by the reaction of a substance with oxygen to produce oxides, commonly releasing energy as heat and light, for instance, CxHy + O2 → CO2 + H2O.

Decomposition Reaction

A decomposition reaction is a type of chemical reaction where a single compound breaks down into two or more simpler substances. The general form of a decomposition reaction is AB → A + B, where AB is the compound that decomposes into elements or simpler compounds A and B.

These reactions often require an initial input of energy in the form of heat, light, or electricity to occur. An example of a decomposition reaction is the electrolysis of water into hydrogen and oxygen gases. The decomposition of hydrogen peroxide into water and oxygen gas, as detailed in the provided exercise (2H2O2 (l) → 2H2O (l) + O2 (g)), is essential for various biological processes and industrial applications.

Reactants and Products

Reactants are substances that undergo chemical change during a reaction, while products are the substances formed as a result of that reaction. In general, a chemical equation takes the form, Reactants → Products.

Identifying and balancing reactants and products is fundamental to understanding and accurately representing chemical reactions. Conserving mass requires that the number of atoms for each element be the same on both sides of the reaction. For example, in the balance equation for the decomposition of hydrogen peroxide (2H2O2 (l) → 2H2O (l) + O2 (g)), there are four hydrogen atoms and four oxygen atoms as reactants and the same number as products, thus complying with the law of conservation of mass.