GCSE Chemistry - Acids and Bases #34

Introduction

This tutorial explores the concepts of acids and bases, the pH scale, measurement techniques for pH, and neutralisation reactions. Understanding these fundamental principles is vital for GCSE Chemistry and provides a foundation for further study in chemistry and environmental science.

Step 1: Understanding Acids and Bases

• Definition of Acids: Substances that release hydrogen ions (H⁺) when dissolved in water. Common examples include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄).
• Definition of Bases: Substances that can accept hydrogen ions or donate hydroxide ions (OH⁻) in solution. Examples include sodium hydroxide (NaOH) and ammonia (NH₃).
• Properties:
  • Acids taste sour, can conduct electricity, and react with metals.
  • Bases feel slippery, taste bitter, and can change the color of indicators.

Step 2: Exploring the pH Scale

• Definition of pH: A measure of how acidic or basic a solution is, ranging from 0 to 14.
  • pH less than 7 indicates an acid.
  • pH of 7 indicates neutrality (pure water).
  • pH greater than 7 indicates a base.
• Significance: The pH level affects chemical reactions, biological processes, and environmental factors.

Step 3: Measuring pH

• Using Indicators:

  • Indicators are substances that change color based on the pH level.
  • Common indicators include litmus paper, phenolphthalein, and bromothymol blue.
  • Procedure for using litmus paper:
    1. Dip the paper into the solution.
    2. Compare the color change to a pH scale chart.

• Using pH Probes:

  • pH probes provide a digital readout of pH levels.
  • Ensure the probe is calibrated according to the manufacturer's instructions.
  • Submerge the probe in the solution and wait for the reading to stabilize.

Step 4: Neutralisation Reactions

• Definition: A reaction between an acid and a base that produces salt and water.
• General Equation:

  Acid + Base → Salt + Water
  

• Example:
  • Hydrochloric acid reacting with sodium hydroxide:

  HCl + NaOH → NaCl + H₂O
  

• Practical Applications:
  • Neutralising acids in soil to improve plant growth.
  • Treating acidic waste in industrial processes.

Conclusion

Understanding acids and bases, the pH scale, measurement techniques, and neutralisation reactions is essential for grasping key concepts in chemistry. These principles not only apply in academic settings but also in real-world scenarios like environmental management and industrial processes. To further your knowledge, consider exploring titration techniques and their applications in determining concentrations of acidic and basic solutions.