Under which conditions would the solubility of a gas in water be greatest?

• A. Low temperature and high pressure
• B. High temperature and high pressure
• C. Low temperature and low pressure
• D. High temperature and low pressure

Answer: (A)

Verified step by step guidance

1. Understand that the solubility of a gas in a liquid is influenced primarily by temperature and pressure.
2. Recall Henry's Law, which states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Mathematically, this is expressed as \(S = k_H \times P\), where \(S\) is solubility, \(k_H\) is Henry's law constant, and \(P\) is the partial pressure of the gas.
3. Recognize that increasing the pressure of the gas above the liquid increases the solubility because more gas molecules are 'pushed' into the solution.
4. Consider the effect of temperature: generally, increasing temperature decreases the solubility of gases in liquids because gas molecules gain kinetic energy and escape more easily from the liquid phase.
5. Combine these concepts to conclude that the greatest solubility of a gas in water occurs at low temperature (to keep gas molecules dissolved) and high pressure (to increase the amount of gas dissolved).