Final answer:
The progress of the reaction can be followed by observing the formation of products and the disappearance of reactants. Measurement of concentration changes and the use of indicators can help track the progress of the reaction.
Step-by-step explanation:
The progress of the given reaction can be followed by observing the formation of products and the disappearance of reactants. In this reaction, sodium sulfite (Na2SO3) reacts with hydrochloric acid (HCl) to form sodium chloride (NaCl), water (H2O), and sulfur dioxide (SO2).
The reaction can be followed by measuring the changes in the concentration of these species over time. For example, the formation of sodium chloride can be observed by an increase in the concentration of NaCl in the solution, while the formation of sulfur dioxide can be monitored by measuring the volume of gas produced.
Another way to track the progress of the reaction is by using indicators. For example, phenolphthalein can be added to indicate the presence of hydroxide ions (NaOH), which are formed during the reaction. The color change of the indicator can be used to determine the endpoint of the reaction.