Question

Write a chemical equation to show the neutralization of hydroiodic acid (HI) by sodium hydroxide (NaOH).

Short answer

The balanced chemical equation for the neutralization of hydroiodic acid (HI) by sodium hydroxide (NaOH) is: HI + NaOH -> H2O + NaI.

Step-by-step solution

Write Reactant Formulas

Identify the reactants which are hydroiodic acid (HI) and sodium hydroxide (NaOH). Write their chemical formulas down.

Write Product Formulas

During neutralization, an acid reacts with a base to form water (H2O) and a salt. The salt formed here would be sodium iodide (NaI). Write down the formulas for water and sodium iodide.

Combine Reactants and Products to Form the Equation

Now that you have the formulas for all reactants and products, combine them to write the chemical equation before balancing: HI + NaOH -> H2O + NaI.

Balance the Chemical Equation

Balance the number of atoms of each element on both the reactant and product sides of the chemical equation. For this reaction, the equation is already balanced as written, so no further steps are required.

Key concepts

Writing Chemical Equations

Understanding how to write chemical equations is foundational to grasping how chemical reactions occur. When we look at the neutralization of hydroiodic acid (HI) by sodium hydroxide (NaOH), we start by identifying the reactants involved. In this case, it is HI, a strong acid, and NaOH, a strong base.

The critical aspect of writing the equation is to accurately represent the reactants and products including their correct formulas. After identifying the reactants, you also need to write down the formulas for the resulting products—water (H2O) and sodium iodide (NaI), which is a salt. With the formula for water being well-known, salt nomenclature follows the cation from the base (Na from NaOH) and the anion from the acid (I from HI), combining to form NaI.

Getting this process down lays a clear path to visualizing the reaction in its entirety and is a key skill in chemistry. Ensure that the reactants are on the left side of the equation and the products on the right, separated by an arrow indicating the direction of the reaction.

Acid-Base Reaction

An acid-base reaction, often referred to as a neutralization reaction, involves an acid and a base reacting to form water and a salt. Exploring our example, hydroiodic acid (HI) donates a proton (H+) to the hydroxide ion (OH-) from sodium hydroxide (NaOH), which is the essence of the acid-base reaction.

This specific type of chemical reaction always produces water, demonstrated here as H2O, due to the combination of H+ and OH- ions. The remaining ions from the reactants form a salt—in this case, sodium iodide (NaI). This reaction highlights the critical neutralization process, emphasizing how opposite pH substances can create a more neutral solution. The fundamental principles of these reactions help us understand processes ranging from digestion in biology to the making of various household products in industry.

Chemical Equation Balancing

Chemical equation balancing is paramount in asserting that matter is neither created nor destroyed in a chemical reaction, in accordance with the Law of Conservation of Mass. Once you have identified the reactants and products, the next step is to ensure that you have the same number of each type of atom on both sides of the equation.

For our exercise, the equation HI + NaOH -> H2O + NaI does not require adjusting the number of atoms or molecules—a rare but convenient occurrence. Normally, you'd adjust coefficients—numbers placed before compounds—to balance atoms on both sides. The simplicity of the equation should not detract from the importance of this skill; balancing more complex reactions requires careful attention to each atom's tally. By mastering balancing, students can be assured that their chemical equations accurately depict the stoichiometry of real-world reactions.