Introduction to Acid- Base Reactions

Introduction to Acid- Base Reactions

Chapter: Introduction to Acid-Base Reactions

Understanding Basic Terms

  • An acid is a substance that donates hydrogen ions in solution. It is also known as a proton donor.
  • A base, on the other hand, is a substance that can accept hydrogen ions.
  • The reaction between an acid and a base is called an acid-base reaction. The main products of this reaction are water and salt.
  • A salt is an ionic compound that is formed when the hydrogen ion of an acid has been replaced by a metal ion.

The pH Scale

  • pH is a measurement of the acidity or alkalinity of a solution. It ranges from 0-14.
  • A pH value of 7 indicates a neutral solution (like pure water).
  • Values below 7 indicate an acidic solution, with 0 being the most acidic.
  • Values above 7 indicate an alkaline or basic solution, with 14 being the most basic/alkaline.

Acid-Base Titration

  • Titration is a common laboratory method used to determine the concentration of an unknown acid or base.
  • The process involves adding a known solution (the titrant) to an unknown solution (the analyte) until the reaction is neutralised. This is usually indicated by a colour change from an indicator.
  • The endpoint of a titration is when the exact amount of titrant has been added to neutralize the analyte.

Indicators in Acid-Base Reactions

  • Indicators are substances that change colour depending on the pH of the solution they are in.
  • Litmus paper is a common indicator which turns red in acidic solutions and blue in basic solutions.
  • Phenolphthalein is another commonly used indicator. It is colorless in an acidic solution and pink in a basic solution.

Buffer Solutions

  • A buffer solution is a system that minimises pH changes when small amounts of an acid or base are added.
  • It is an equilibrium system that consists of a weak acid and its conjugate base, or a weak base and its conjugate acid.
  • Buffer solutions are important in many biological systems that require a specific and consistent pH level.

Acid Rain

  • Acid rain is a result of pollution in the atmosphere which causes the rainwater to become more acidic than normal.
  • It is harmful to the environment, causing damage to buildings, soil, water bodies, and living organisms.
  • It is usually caused by the release of sulphur dioxide and nitrogen oxide during fossil fuel combustion.