The percentage change in mass, a normalized metric, enables students to compare the impact of various sodium chloride concentrations on onions. This facilitates interpretation and comparison of results across experimental conditions.
The students calculated the percentage change in mass of the onions to assess and quantify the effect of soaking the small onion bulbs in different concentrations of sodium chloride solution.
By measuring the change in mass before and after the three-hour soaking period, they can evaluate the impact of the salt solution on the onions.
The percentage change in mass is a useful metric because it normalizes the mass change relative to the initial mass of the onions. This allows for a standardized comparison of the effects of different concentrations of sodium chloride on the onions, irrespective of their initial size or mass. The percentage change in mass is calculated using the formula:
Percentage Change = ((Final Mass - Initial Mass) / Initial Mass) * 100
By expressing the change in mass as a percentage of the initial mass, the students can easily compare the responses of onions in different batches and concentrations of sodium chloride.
This approach helps them determine whether the onions absorbed water (resulting in an increase in mass), lost water (resulting in a decrease in mass), or remained relatively unchanged in mass.
The percentage change provides a standardized measure that facilitates the interpretation and comparison of the results across different experimental conditions.
Complete question:
A group of students investigated the effect of soaking small onion bulbs in different concentrations of sodium chloride solution. They peeled off the outer papery leaves of the onion bulbs and divided the onions into 6 batches, each with 10 onions. The onions were surface dried with paper towels and weighed. The mean mass of the onions in each batch was calculated. The onions were then left in sodium chloride solutions for three hours. After three hours the students surface dried the onions and weighed them again. Explain why the students calculated the percentage change in mass of the onions.