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.

24. Suppose that a sixth KI/H2O solution had been measured in Experiment 2 and the mass of the solution in the graduated cylinder was 67.54 g. The density of this solution would most likely have been closest to which of the following?

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

Looking at table 2, it can be seen that the density of the solution in the graduated cylinder mass increases by about 0.04-0.06 g/mL for every 3 g increase.

The solution in the graduated cylinder mass given in the question stem is 67.54 g, which is larger than the solution in the graduated cylinder mass of liquid 10 64.64 g, 67.54-64.64=2.90 g. So the density of the solution is expected It is also about 0.04-0.06 mL larger than the density of liquid 10 (1.29 mL), which is about 1.33-1.35 mL