Question

Explain why pressure affects the solubility of \(\mathrm{O}_{2}\) in water, but not the solubility of \(\mathrm{NaCl}\) in water.

Short answer

In summary, pressure affects the solubility of \(\mathrm{O}_{2}\) in water because, according to Henry's Law, the solubility of a gas is directly proportional to its partial pressure. As pressure increases, more gas molecules are forced into the liquid, increasing solubility. However, pressure does not significantly affect the solubility of a solid like \(\mathrm{NaCl}\) in water, since the dissolution process relies more on temperature and the properties of the solute and solvent, rather than pressure.

Step-by-step solution

Understanding solubility

Solubility is the ability of a substance to dissolve in a solvent. In this situation, the substances are \(\mathrm{O}_{2}\) (gas) and \(\mathrm{NaCl}\) (salt), and the solvent is water. The solubility of a substance depends on various factors, including temperature, pressure, and the nature of the substance and solvent.

How pressure affects the solubility of gases

According to Henry's Law, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. This means that when the pressure of a gas above the liquid increases, the gas molecules are pushed more forcefully into the liquid, causing more gas to dissolve. In the case of \(\mathrm{O}_{2}\) in water, an increase in pressure will lead to higher solubility as more oxygen molecules are forced into the liquid.

How pressure affects the solubility of solids

The solubility of a solid in a liquid, such as \(\mathrm{NaCl}\) in water, is not significantly affected by pressure. This is because the dissolution process of a solid in a liquid involves breaking the solid's crystal lattice, which is not dependent on pressure. The solubility of a solid is mainly influenced by temperature and the nature of the solute and solvent.

Conclusion

To sum up, pressure affects the solubility of \(\mathrm{O}_{2}\) in water because the solubility of a gas is directly proportional to the partial pressure of the gas, as explained by Henry's Law. However, pressure does not significantly influence the solubility of a solid like \(\mathrm{NaCl}\) in water, as the dissolution process of a solid is mainly dependent on temperature and the nature of the substances involved, rather than pressure.