Question

Complete and balance the following equations. If no reaction occurs, write NR: (a) \(\mathrm{Rb}(s)+\mathrm{Br}_{2}(l) \longrightarrow\) (b) \(\mathrm{I}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\) (c) \(\mathrm{Br}_{2}(l)+\mathrm{I}^{-}(a q) \longrightarrow\) (d) \(\mathrm{CaF}_{2}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(l) \longrightarrow\)

Short answer

a) \text{2Rb} + \text{Br}_2 \rightarrow \text{2RbBr}, b) \text{NR}, c) \text{Br}_2 + 2\text{I}^- \rightarrow 2\text{Br}^- + \text{I}_2, d) \text{CaF}_2 + \text{H}_2\text{SO}_4 \rightarrow 2\text{HF} + \text{CaSO}_4

Step-by-step solution

Identify Reactants and Products

For each part of the exercise, identify the reactants given and predict the products based on common reaction types.

Write Unbalanced Equations

Write the skeleton of the chemical equations with the predicted products for each of the reactions.

Balance Each Equation

Ensure that the number of atoms of each element is the same on both sides of the equations to comply with the Law of Conservation of Mass.

Determine if No Reaction Occurs

For cases where no reaction occurs, denote the equation with NR.

Key concepts

chemical reactions

A chemical reaction occurs when substances, known as reactants, are transformed into different substances, known as products. This change happens due to the breaking and forming of chemical bonds between atoms. Understanding the basics of chemical reactions helps us see how materials interact and change.
There are different types of chemical reactions, including:

• Synthesis reactions, where multiple reactants combine to form one product
• Decomposition reactions, where one reactant breaks down into multiple products
• Single replacement reactions, where one element replaces another in a compound
• Double replacement reactions, where the ions of two compounds exchange places

Knowing these types helps in predicting the products of a reaction and balancing equations correctly.

reactants and products

In a chemical equation, reactants are the starting substances that undergo a change, while products are the new substances formed as a result of the reaction.
For example, in the reaction: \( \text{Rb}(s) + \text{Br}_2(l) \rightarrow \text{RbBr}(s) \), \( \text{Rb} \) and \( \text{Br}_2 \) are the reactants, and \( \text{RbBr} \) is the product.
Understanding the nature of reactants and predicting the products based on common reaction types is a crucial step in solving and balancing chemical equations. Each reactant and product must be identified accurately to ensure the reaction is fully understood, as demonstrated in the provided exercise and solution.

law of conservation of mass

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. This means that the total mass of reactants must equal the total mass of products. In practice, this requires us to balance chemical equations so that the number of each type of atom is the same on both sides of the equation.
For instance, in balancing the equation: \( \text{CaF}_2(s) + \text{H}_2\text{SO}_4(l) \rightarrow \text{CaSO}_4(s) + 2\text{HF}(g) \), both sides of the equation have 1 Calcium (Ca), 2 Fluorines (F), 1 Sulfur (S), and 4 Oxygens (O), ensuring mass is conserved.
It's a universal principle that always applies, whether in simple reactions or more complex ones. This principle ensures that chemical equations accurately represent what occurs during reactions.