Final answer:
If the Na₂S₂O₃ stock solution was twice as concentrated as intended, the measured time of each reaction in the experiment would likely be faster.
Step-by-step explanation:
If the Na₂S₂O₃ stock solution was twice as concentrated as intended, it would have a significant effect on the measured time of each reaction in the experiment. Generally, the concentration of a solution affects the rate of a reaction.
In this case, a more concentrated Na₂S₂O₃ solution would likely result in faster reaction times. For example, if the reaction involves the reduction of iodine by thiosulfate ions, a more concentrated Na₂S₂O₃ solution would supply more thiosulfate ions to react with the iodine, leading to a faster reaction.
This would decrease the measured time for the reaction compared to the intended concentration. Overall, doubling the concentration of the Na₂S₂O₃ stock solution would likely decrease the measured time of each reaction, making them appear to occur more quickly.