Chemistry – Acids, bases and salts - The characteristic properties of acids and bases | e-Consult

Two pieces of equipment the student could use to monitor the progress of the reaction are:

1. An indicator (e.g., universal indicator or litmus paper): An indicator is a substance that changes colour depending on the pH of the solution. The student could add a few drops of indicator to the conical flask. As the reaction proceeds and the solution becomes more neutral, the colour of the indicator will change from acidic (e.g., red) to neutral (e.g., green) and finally to alkaline (e.g., blue). This provides a visual indication of the reaction's progress and when complete neutralisation has occurred.
2. A pH meter: A pH meter is an electronic instrument that measures the pH of a solution. The student could insert the pH probe into the conical flask and monitor the pH reading as the NaOH is added. The pH will gradually increase as the reaction proceeds towards neutrality. When the pH reaches approximately 7, the reaction is considered complete. The pH meter provides a more precise measurement of the acidity/alkalinity than an indicator.