Question

experiment | predicted observation (choose one)
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. | ∘ a bigger mass of nacl precipitate will form in sample #2. ∘ a smaller mass of nacl precipitate will form in sample #2. ∘ the same mass of nacl precipitate will form in sample #2. ∘ no precipitate will form in sample #2. ∘ i need more information to predict whether and how much precipitate will form in sample #2.
a student sees tiny bubbles clinging to the inside of an unopened plastic bottle full of carbonated soft drink. the student squeezes the bottle. | ∘ the bubbles will shrink, and some may vanish. ∘ the bubbles will grow, and more may appear. ∘ the bubbles wont change. ∘ i need more information to predict what will happen to the bubbles.

Explanation:

First Experiment (NaCl Precipitation)

The solubility of NaCl in water changes slightly with temperature, but it is relatively insoluble and its solubility has a weak positive correlation with temperature (increases a bit with higher temp). Sample #1 (42°C initially) and Sample #2 (8°C initially) are both brought to 20°C (room temp) and 1 atm. Since no precipitate formed in Sample #1 at 20°C, and the solubility change with temperature for NaCl is minimal, when Sample #2 (cooler initially) is brought to 20°C, its solubility at 20°C will be similar to Sample #1 at 20°C. So no precipitate should form in Sample #2.

Carbonated drinks have dissolved CO₂ under pressure. When the bottle is squeezed, the pressure inside increases. According to Henry's Law, the solubility of a gas (CO₂) in a liquid (the drink) increases with increasing pressure. So more CO₂ will dissolve, causing the bubbles (which are CO₂ gas) to shrink or vanish as the gas dissolves back into the liquid.

Answer:

No precipitate will form in Sample #2.

Second Experiment (Carbonated Soft Drink Bubbles)