Question

rock candy is formed when excess sugar is dissolved in hot water followed by crystallization. a student wants to make two batches of rock candy. he finds an unopened box of \cane sugar\ in the pantry. he starts preparing batch a by dissolving sugar in 500 ml of hot water (70°c). he keeps adding sugar until no more sugar dissolves in the hot water. he cools the solution to room temperature. he prepares batch b by dissolving sugar in 500 ml of water at room temperature until no more sugar is dissolved. he lets the solution sit at room temperature.
a student sees tiny bubbles clinging to the inside of an unopened plastic bottle full of carbonated soft drink. the student opens the bottle, and hears a loud hiss as gas under pressure escapes from the bottle.

Explanation:

For the rock candy problem:

• The solubility of sugar in water increases with temperature. In batch A, sugar is dissolved in hot water ($70^{\circ}C$) until no more dissolves. When cooled to room temperature, the solubility of sugar decreases. The amount of sugar dissolved in hot water (batch A) is more than that in room - temperature water (batch B). As the solution cools, the excess sugar (beyond the solubility at room temperature) will crystallize to form rock candy. So, more rock candy will form in batch A.

For the carbonated drink problem:

• Carbonated soft drinks have carbon dioxide gas dissolved in them under pressure. When the bottle is opened, the pressure inside the bottle decreases. According to Henry's law (the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid), the solubility of carbon dioxide in the drink decreases. The gas that was previously dissolved will start to come out of the solution. The existing bubbles (which are likely small pockets of carbon dioxide) will grow as more gas comes out of the solution, and more bubbles may form.

Answer:

For the rock candy problem: It is likely that more rock candy will be formed in batch A.
For the carbonated drink problem: The bubbles will grow, and more may appear.