Question

Write a balanced equation for each of the following decomposition reactions: (a) Calcium nitrate decomposes on heating to give solid calcium nitrite and oxygen gas. (b) Silver sulfate decomposes on heating to give solid silver sulfite and oxygen gas.

Short answer

Balanced equations are: (a) \( ext{2Ca}( ext{NO}_3)_2 ightarrow 2 ext{Ca}( ext{NO}_2)_2 + ext{O}_2 \). (b) \( ext{2Ag}_2 ext{SO}_4 ightarrow 2 ext{Ag}_2 ext{SO}_3 + ext{O}_2 \).

Step-by-step solution

Write the Reactants and Products

For each reaction, start by identifying the reactants and products. In reaction (a), the reactant is calcium nitrate (\( ext{Ca}( ext{NO}_3)_2\)) which decomposes into calcium nitrite (\( ext{Ca}( ext{NO}_2)_2\)) and oxygen gas (\( ext{O}_2\)). In reaction (b), the reactant is silver sulfate (\( ext{Ag}_2 ext{SO}_4\)), which decomposes into silver sulfite (\( ext{Ag}_2 ext{SO}_3\)) and oxygen gas (\( ext{O}_2\)).

Key concepts

Chemical Equations

A chemical equation is a way of representing a chemical reaction using symbols and formulas. It shows the substances that are involved, namely the reactants (starting materials) and products (resulting substances). Consider it like a recipe, but for chemicals. In the exercise given, we have decomposition reactions where a single compound breaks down into two or more substances. For example:

• For calcium nitrate, the chemical equation can be written as: \(\text{Ca}(\text{NO}_3)_2 \rightarrow \text{Ca}(\text{NO}_2)_2 + \text{O}_2\).
• For silver sulfate, it becomes: \(\text{Ag}_2\text{SO}_4 \rightarrow \text{Ag}_2\text{SO}_3 + \text{O}_2\).

Each part of the equation has its own specific symbol. Reactants are on the left, and products are on the right, separated by an arrow which indicates the direction of the reaction. Such equation provides crucial information about the involved chemical processes.

Balancing Equations

Balancing equations is a vital step in writing chemical equations. It ensures that the law of conservation of mass is followed. This law states that matter cannot be created or destroyed in a chemical reaction. Therefore, the same number of each type of atom must appear on both sides of the equation.To balance a chemical equation:

• Write the unbalanced equation using the correct formulas for all reactants and products.
• Count the number of atoms for each element in both the reactants and products.
• Adjust the coefficients (numbers in front of the formulas) to balance the atoms on each side.

For instance, if we look at the decomposition of calcium nitrate:

• The initial equation is: \(\text{Ca}(\text{NO}_3)_2 \rightarrow \text{Ca}(\text{NO}_2)_2 + \text{O}_2\).
• Here, calcium and nitrite atoms already balance on both sides. However, check the oxygen atoms to ensure balance.
• Adjust the coefficients where necessary to ensure the counts match.

Balancing ensures the equation abides by real-world expectations of matter conservation.

Chemical Reactions

Chemical reactions are processes where reactants are transformed into products. They are distinguished by changes that they cause, like energy release or absorption, changes in color, or formation of precipitates. In decomposition reactions specifically, a single compound breaks down into simpler compounds or elements.

• For calcium nitrate, heat causes it to decompose into calcium nitrite and oxygen gas.
• For silver sulfate, it similarly decomposes when heated into silver sulfite and oxygen gas.

These reactions are crucial as they provide insights into energy changes and how substances can interact under different conditions. Understanding these reactions help in predicting the behavior of substances when subjected to specific changes. Keep in mind, not all reactions are immediately apparent just through observation. Using equations and balancing them allows for a clear understanding of all involved components and transformations.