Question

predict what will be observed in each experiment below.
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.
two 250 ml samples of water are drawn from a deep well bored into a large underground salt (nacl) deposit. sample #1 is from the top of the well, and is initially at 42°c. sample #2 is from a depth of 150 m, and is initially at 8°c. both samples are allowed to come to room temperature (20°c) and 1 atm pressure. an nacl precipitate is seen to form in sample #1.

Explanation:

Problem 1:

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. As the pressure decreases, the solubility of carbon - dioxide (the gas that forms bubbles in carbonated drinks) in the liquid decreases. So, the bubbles (which are mainly carbon - dioxide gas) will grow (because the gas comes out of the solution) and more may appear as the gas continues to escape from the supersaturated solution.

The solubility of NaCl in water increases with temperature. Sample #1 is initially at \(42^{\circ}C\) and cools to \(20^{\circ}C\), and a precipitate forms. Sample #2 is initially at \(8^{\circ}C\) and warms to \(20^{\circ}C\). Since the solubility of NaCl increases with increasing temperature, when Sample #2 warms up, the amount of NaCl that can be dissolved in the water increases. So, a smaller mass of NaCl precipitate will form in Sample #2 compared to Sample #1 (because Sample #1 was cooling down and losing solubility, while Sample #2 is warming up and gaining solubility).

Answer:

The bubbles will grow, and more may appear.

Problem 2: