The neutralization of a 0.455 g sample of recrystallized aspirin required 38.6 mL of 0.100 M NaOH solution. An additional 25.0 mL of 0.100 M NaOH was added to the sample to hydrolyze the neutralized aspirin in the solution. The solution was heated. Phenolphthalein was added to the cooled solution and was back-titrated with 11.2 mL of 0.100 M HCl. Determine the mass percent of the sample

what are the choices?

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.