Question

Write a balanced equation for each of each of the following decomposition reactions: (a) Stannous chlorate decomposes on heating to give solid stannous chloride and oxygen gas. (b) Plumbic oxide decomposes on heating to give solid plumbous oxide and oxygen gas.

Short answer

(a) \( \text{Sn(ClO}_3)_2 \rightarrow \text{SnCl}_2 + 2\text{O}_2 \); (b) \( 2\text{PbO}_2 \rightarrow 2\text{PbO} + \text{O}_2 \).

Step-by-step solution

Identify Reactants and Products for Reaction (a)

The reaction involves the decomposition of stannous chlorate (\( \text{Sn(ClO}_3)_2 \)) that breaks down into stannous chloride (\( \text{SnCl}_2 \)) and oxygen gas (\( \text{O}_2 \)). The chemical reaction is thus from one compound breaking down into two products.

Write and Balance the Equation for Reaction (a)

First, write the unbalanced equation: \[ \text{Sn(ClO}_3)_2 \rightarrow \text{SnCl}_2 + \text{O}_2 \]. Count atoms on each side to ensure they're equal. Since each chlorate contributes two oxygens, we end up needing 2 moles of \( \text{O}_2 \) to match the four oxygens from the reactant. The balanced equation is: \[ \text{Sn(ClO}_3)_2 \rightarrow \text{SnCl}_2 + 2\text{O}_2 \].

Identify Reactants and Products for Reaction (b)

The second reaction involves the decomposition of plumbic oxide (\( \text{PbO}_2 \)) which breaks down into plumbous oxide (\( \text{PbO} \)) and oxygen gas (\( \text{O}_2 \)). This also involves a compound decomposing into simpler products.

Write and Balance the Equation for Reaction (b)

Write the unbalanced equation: \[ \text{PbO}_2 \rightarrow \text{PbO} + \text{O}_2 \]. For balance, we check the number of oxygen atoms. We need two \( \text{PbO}_2 \) to produce an equal number of \( \text{PbO} \) and \( \text{O}_2 \). Thus, the balanced equation is: \[ 2\text{PbO}_2 \rightarrow 2\text{PbO} + \text{O}_2 \].

Key concepts

Decomposition Reactions

Decomposition reactions are a fundamental type of chemical reaction in which a compound breaks down into two or more simpler substances. These reactions are characterized by one reactant yielding multiple products.
For example, in the decomposition of stannous chlorate, the compound breaks into stannous chloride and oxygen gas. The general form can be written as:

• \[ ext{AB} ightarrow ext{A} + ext{B} \]

These reactions often require an input of energy in the form of heat, light, or electricity to overcome the bond energies within the reactant compound, like when heating plumbic oxide leads to its decomposition.
Understanding the nature of decomposition reactions is essential for predicting the products formed during a chemical reaction.

Balancing Chemical Equations

Balancing chemical equations is an important skill in chemistry that ensures the law of conservation of mass is applied. This means that the number of atoms for each element must be the same on both sides of the equation.
The process involves the following steps:

• **Write the unbalanced equation**: Start by noting down the reactants and products in their chemical form.
• **Count the number of atoms of each element**: Ensure each atom is balanced on both sides of the reaction.
• **Adjust coefficients to balance the equation**: Unlike changing subscripts, only coefficients before compounds are adjusted to balance an equation. For instance, in the equation for the decomposition of stannous chlorate, a coefficient of 2 before \(\text{O}_2 \) was needed to balance the oxygens.
• **Check your work**: Recount atoms to ensure that the number from each element matches on both sides. One small miscalculation can throw off the balance.

Balancing equations requires practice to quickly identify how to efficiently balance more complex reactions. Once mastered, this skill greatly enhances the understanding of chemical reactions.

Chemical Reactions

Chemical reactions are processes where substances, known as reactants, are transformed into different substances, known as products. These reactions are central to the field of chemistry and occur everywhere around us.
The nature of a chemical reaction can vary greatly:

• **Types**: There are several basic types, including synthesis, decomposition, single replacement, and double replacement reactions.
• **Indicators**: Reactions often involve noticeable changes such as color change, gas production, or temperature change.
• **Energy Changes**: They either absorb energy (endothermic) or release energy (exothermic).

Understanding chemical reactions involves grasping how reactants interact at the molecular level to form novel products. For instance, knowing the nature of decomposition reactions helps predict the possible breakdown products, like oxygen gas being a common by-product.
Overall, chemical reactions are essential for understanding material interactions and have practical applications in industries, laboratories, and everyday life.