Solubility

Section 1: Fundamental Concepts of Solubility

• Solubility is the maximum amount of a solute that can be dissolved in a definite amount of solvent at a specific temperature.
• This process is influenced by factors such as temperature, pressure, and the nature of the solvent and solute.
• Solvents can be classified as polar or non-polar. Polar solvents, like water, tend to dissolve polar solutes, while non-polar solvents, like oil, tend to dissolve non-polar solutes. This is often summed up as ‘like dissolves like’.
• The units of concentration can be given in g/dm³, mol/dm³ or mol/kg, depending on the situation.

Section 2: Solubility and Temperature

• Generally, for most solid solutes, solubility increases as the temperature increases. However, this is not always the case for gases.
• For gaseous solutes, solubility usually decreases as temperature increases.
• This can be observed in everyday instances, such as sugar dissolving more easily in hot tea than in cold water, or a can of soda losing its carbonation when opened at room temperature.

Section 3: Solubility and Pressure

• Pressure has little effect on the solubility of solid and liquid solutes, but has a noticeable impact on gaseous solutes.
• According to Henry’s Law, the solubility of a gas is directly proportional to the pressure of the gas above the solution.

Section 4: Supersaturated Solutions

• A supersaturated solution contains more solute than it should theoretically be able to hold at a given temperature. These are usually created by dissolving the solute in heated solvents and then slowly cooling it.
• Supersaturated solutions are highly unstable and can rapidly precipitate or crystallise when disturbed, producing fascinating formations.

Mastering the concept of solubility can help you understand many relevant phenomena at the molecular level, such as the process of dissolving, the formation of solutions, and the concept of saturation.