Question 9 Answer and Explanation _ACT April 2021 Form Z04 Science Section

Passage II

When certain substances are added to diet cola, CO₂ gas is produced, generating a foam. Two experiments were done to study this process.

In each trial, an apparatus like that shown in Figure 1 was used as follows: A jar was nearly filled with H₂O and fitted with a 2-holed lid. One end of a tube (Tube B) was inserted through one of the holes and submerged. The other end of Tube B was placed in an empty graduated cylinder. Another tube (Tube A) was inserted through the other hole in the lid. A certain solid substance was inserted into the other end of Tube A, and the substance was secured by a clamp. Tube A was then attached to a freshly opened bottle containing 355 mL of diet cola. The clamp was removed, releasing the substance into the diet cola. The foam that was produced traveled into the jar, and liquid was transferred into the cylinder. The mass of CO₂ produced was calculated based on the volume of liquid that was measured in the cylinder after foaming had ceased.

Experiment 1

In each of Trials 1−4, a different 1 of 4 substances of equal mass—a piece of chalk, a sugar cube, a fruit-flavored piece of candy, or a mint-flavored piece of candy—was added to a bottle of diet cola at 3°C. See Table 1.

Experiment 2

In each of Trials 5−8, Trial 4 from Experiment 1 was repeated, except that the temperature of the diet cola was different in each trial. See Table 2.

Tables 1 and 2 adapted from Christopher J. Huber and Aaron M. Massari, "Quantifying the Soda Geyser." ©2014 by Division of Chemical Education, Inc., American Chemical Society.

9. Suppose Trial 6 had been repeated, but the bottle of diet cola had been opened and then left undisturbed at 25°C for 12 hours before it was attached to the apparatus. Would the mass of CO₂ produced in this trial likely be greater than 0.969 g or less than 0.969 g ?

A. Greater, because over the 12 hours, the concentration of CO₂ in the diet cola would have decreased.

B. Greater, because over the 12 hours, the concentration of CO₂ in the diet cola would have increased.

C. Less, because over the 12 hours, the concentration of CO₂ in the diet cola would have decreased.

D. Less, because over the 12 hours, the concentration of CO₂ in the diet cola would have increased.

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

General knowledge questions. The carbonic acid in Coke is very unstable, and the carbon dioxide will slowly precipitate out when the lid is opened, so if the experiment is carried out again, the amount of carbon dioxide obtained will be less than originally planned.