Passage V

Students performed the following experiments to determine the density of common plastics.Experiment 1

A dry 100 mL graduated cylinder was placed on an electronic balance and tared (the balance was reset to 0.000 g). H2O was added to the graduated cylinder until a certain mass was obtained. Ethanol was added to the graduated cylinder until the volume of liquid was 50.0 mL. The density of the liquid was then calculated. The procedure was repeated with different amounts of ethanol and H2O (see Table 1).

Experiment 2

A known mass of potassium iodide (KI) was dissolved in a known mass of H2O. A dry 100 mL graduated cylinder was placed on the balance and tared. The solution was added to the graduated cylinder until the volume was 50.0 mL. The density of the liquid was then calculated. The procedure was repeated with different amounts of KI and H2O (see Table 2).

Experiment 3

A solid plastic bead was placed at the bottom of a sample of each of Liquids 1-10 from Experiments 1 and 2. If the bead stayed at the bottom, “S” was recorded in Table 3. If the bead rose, “R” was recorded in Table 3. The procedure was repeated for various plastics.

27. A student claimed that polycarbonate is more dense than PA-6. Do the results of Experiments 1-3 support his claim?

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

Looking at table 3, the ups and downs of polycarbonate float up in liquids 9-10, and sink to the bottom in other cases, indicating that the density of polycarbonate is less than that of liquids 9;

However, the ups and downs of PA-6 It floats up in liquids 8-10, and sinks to the bottom in other cases, indicating that the density of PA-6 is less than that of liquid 8.

According to table 2, it can be seen that the density of liquid 9 is greater than that of liquid 8, so the density of polycarbonate is greater than that of PA-6. The statement in the question stem is correct