Question

5\. Manganese metal reacts with HCl to give hydrogen gas and the \(\mathrm{Mn}^{2+}\) ion in solution. Write a balanced equation for the reaction.

Short answer

Mn + 2HCl → H₂ + MnCl₂

Step-by-step solution

Identify Reactants and Products

Determine the reactants and products in the reaction. Manganese metal reacts with hydrochloric acid to produce hydrogen gas and the manganese ion. Reactants: Mn and HCl. Products: H₂ and Mn²⁺.

Write Unbalanced Equation

Write the chemical formula for each reactant and product. Mn + HCl → H₂ + Mn²⁺.

Balance the Manganese Atoms

There is 1 manganese atom on both sides of the equation. Mn + HCl → H₂ + Mn²⁺.

Balance the Hydrogen Atoms

There are 2 hydrogen atoms on the product side (H₂). Therefore, we need 2 HCl molecules to provide 2 hydrogen atoms. Mn + 2HCl → H₂ + Mn²⁺.

Balance the Chlorine Atoms

There are 2 chlorine atoms from 2 HCl molecules. We need 2 Cl⁻ ions to balance the chlorine on the product side. Mn + 2HCl → H₂ + MnCl₂.

Final Balanced Equation

Confirm all atoms are balanced. Mn + 2HCl → H₂ + MnCl₂. This is the balanced chemical equation for the reaction.

Key concepts

chemical reactions

Chemical reactions are processes where reactants are transformed into products. In the exercise, manganese metal reacts with hydrochloric acid. This reaction is a type of chemical reaction. It shows how substances can change and form new compounds.
Not every reaction is the same. Some are quick, while others are slow. Some release energy (exothermic), and some absorb energy (endothermic).
Understanding chemical reactions helps in many fields like medicine, environmental science, and engineering.

stoichiometry

Stoichiometry helps us understand the amount of each substance involved in a chemical reaction. It is based on the conservation of mass principle. This means that the total mass of the reactants equals the total mass of the products.
By using stoichiometry, we can predict how much of each reactant is needed, or how much product will be formed. For example, in our exercise, stoichiometry helps us understand how much HCl is needed to react with a given amount of manganese to produce hydrogen gas and MnCl₂.
This makes stoichiometry a powerful tool in chemistry.

reactants and products

Reactants are the starting materials in a chemical reaction, while products are the substances formed as a result. In the exercise, the reactants are manganese metal (Mn) and hydrochloric acid (HCl). The products are hydrogen gas (H₂) and manganese chloride (MnCl₂).
Identifying reactants and products is the first step in writing a chemical equation.

• Reactants: Mn and 2HCl
• Products: H₂ and MnCl₂

This identification helps us understand what changes occur during the reaction.

balancing equations

Balancing equations ensures that the same number of atoms of each element are present on both sides of the equation. This follows the law of conservation of mass. In our example, we start by writing the unbalanced equation:
Mn + HCl → H₂ + Mn²⁺
Next, we balance the manganese atoms (1 Mn on both sides).
Mn + HCl → H₂ + Mn²⁺
Then, we balance the hydrogen atoms. Since there are 2 hydrogen atoms in H₂, we need 2 HCl molecules.
Mn + 2HCl → H₂ + Mn²⁺
Finally, we balance the chlorine atoms. With 2 HCl molecules, we get 2 Cl⁻ ions, forming MnCl₂:
Mn + 2HCl → H₂ + MnCl₂
This balanced equation accurately represents the reaction.