Chapter 6, Problem 34A

Summary Introduction

To write:

The ions formed when HCl dissolves in water and the effect it has on pH of water.

Introduction:

Solutions are homogeneous mixtures formed when a solute is dissolved in a solvent. There are two components in a solution- solvent and solute. The solvent is a substance in which another substance is dissolved. A solute is a substance that is dissolved in the solvent.

Explanation of Solution

When a substance that contains hydrogen is dissolved in water, it may release a hydrogen ion (H⁺) because it is attached to the negatively charged oxygen atoms in water. Acids are the substances that release hydrogen ions when dissolved in water. The more hydrogen ions a substance releases, the more acidic is the solution. pH is the measure of concentration of hydrogen ions (H⁺) in a solution. Pure water is neutral and has a pH value of 7.0. HCl molecule is composed of a hydrogen atom and a chlorine atom. When it is dissolved in water, it will release H+ ions. The increase in the H+ ions will lower the pH of water. Acidic solutions have more H+ and have pH values less than 7.

Conclusion

Acids are substances that release hydrogen ions when dissolved in water. HCl will release hydrogen ions and lower the pH.