In analyzing the experiment where sulfuric acid ([tex]$H_2SO_4$[/tex]) reacts with varying volumes of sodium thiosulfate and water, we start by observing Flask 1 as our reference. Here, 5 mL of sulfuric acid is reacted with 50 mL of sodium thiosulfate and no additional water, resulting in a reaction time of 19 seconds.
In Flasks 2, 3, and 4, the volume of sodium thiosulfate decreases progressively as the volume of water increases. Based on the principles of reaction kinetics, specifically the concentration of reactants, we can predict that:
1. Flask 2: Contains 5 mL of sulfuric acid, 40 mL of sodium thiosulfate, and 10 mL of water.
2. Flask 3: Contains 5 mL of sulfuric acid, 30 mL of sodium thiosulfate, and 20 mL of water.
3. Flask 4: Contains 5 mL of sulfuric acid, 20 mL of sodium thiosulfate, and 30 mL of water.
As we move from Flask 1 to Flask 4, the concentration of sodium thiosulfate in the mixture decreases due to the increasing amount of water. A lower concentration of sodium thiosulfate means that there are fewer thiosulfate ions available to react with the sulfuric acid, thus slowing down the reaction rate.
Since we know that reaction rate is directly proportional to the concentration of reactants, a decrease in the concentration of one of the reactants (in this case, sodium thiosulfate) will result in a slower reaction.
Therefore, we can conclude that:
- The reaction time in Flask 2 will be slightly longer than in Flask 1 (more than 19 seconds).
- The reaction time in Flask 3 will be longer than in Flask 2.
- The reaction time in Flask 4 will be the longest among all flasks.
In summary, the trend of the reaction times as we progress from Flask 1 to Flask 4 is an increase in reaction time. This trend occurs because the decreased concentration of sodium thiosulfate, due to its dilution with water, leads to a decrease in the rate of the chemical reaction.
