How Does Temperature Affect the Rate of Dissolving?
Whether the solute is a solid or gas, its solubility in water is dependent on temperature such that an increase in temperature can make solids more soluble while gases become less soluble. This means that if the temperature of water is increased by heating it, then the solid solute will dissolve more quickly. However, for gases dissolved in water, the reverse occurs and solubility decreases with an increase in water temperature.
Using cocoa powder and placing it in a cup with boiling water can demonstrate temperature's effect on a solid's rate of dissolving, or its solubility in water. A second cup containing cold water and cocoa powder is used for comparison of solubility rates. The comparison demonstrates that the cocoa powder poured into a cup of boiling water dissolves more quickly than the powder placed in cold water.
An example of the effects of temperature on gas dissolving in a liquid is opening a cold soda can and leaving it out at room temperature. After a time, the soda tastes flat due to a decrease in gas solubility.