It is a common observation that warm water dissolves sugar more quickly than cold water. Temperature is just one of the factors that influence solubility. Nature of solute/solvent, pressure, particle size and mechanical motion, also affect the solubility of a solute. Let’s look at all of them in depth:
-Temperature:
Various solutes/solvents behave differently with change in temperature.
Water is the universal solvent. The solubility of water increases with temperature. The only exception is that when the temperature increases too much, the solubility of ionic solutes decreases. But, in water, the solubility of organic solutes, like sugar, glucose etc, increase with rise in temperature.
Likewise, organic solvents show high solubility with raise in temperature. This is also true for gases if they are dissolved in organic solvents. But in water the solubility of gases goes down as the temperature increases.
-Nature of solute/solvent:
Polarity plays a pivotal role in solubility. A polar solute will dissolve in a polar solvent whereas a non-polar solvent will dissolve in a non-polar solvent. If we put a polar solute in a non-polar solvent, it won’t dissolve.
To remove paint from clothes we don’t use water, we use an organic solvent, like acetone or petrol. Paint is non-polar, and to dissolve it we need a non-polar solvent like acetone.
-Pressure:
Pressure only affects the solubility of gases in liquid solvents. If we increase the pressure of a gas that is inside a container with liquid in it, the solubility of the gas will increase.
If you pass Carbon-dioxide from water at atmospheric pressure, it will barely dissolve. But this process is quickly done by increasing the pressure of CO2.
It is important here to learn the term “Partial Pressure”. In a mixture of gases, partial pressure of any one gas is the pressure it will have had it occupied the entire volume. When dissolving a gas in a solvent, we increase the pressure of that gas inside the container.
All the Soda drinks are made by dissolving CO2 in them.
-Size of Particles
The smaller the size of particles of solute, the faster will it dissolve in a liquid solvent. For example, powdered sugar or salt dissolves rapidly as compared to crystalline form.
-Mechanical Motion
Most of the solutes barely dissolve in a liquid solvent if they are not stirred. Mechanical Motion, like stirring or whirling or shaking affects the solubility of a solid solute in a liquid solvent.
