Temperature and Solubility of Salt vs. Sugar

This demonstration compares how temperature affects the dissolving of sugar versus salt in hot and cold water. Students observe that sugar dissolves much more in hot water than in cold, while salt shows little difference.

1. Label two small cups “salt” and two small cups “sugar.”
2. Place one tablespoon of salt in each salt cup and one tablespoon of sugar in each sugar cup.
3. Pour 25 mL of hot water (about 50 °C) into one graduated cylinder and 25 mL of cold water (about 5 °C) into another.
4. At the same time, pour salt from the two salt cups into the hot and cold water cylinders without stirring.
5. Repeat the same process with sugar in two more graduated cylinders.
6. Observe and compare the amount of undissolved solid left in each cylinder.

Video lab: Solubility & Temperature - ScienceGonnaGetYou:

📄 Does Temperature Affect Dissolving? - ACS: https://www.acs.org/middleschoolchemistry/lessonplans/chapter5/lesson6.html

• Stir the solutions gently and compare results with unstirred samples.
• Try using other solutes, such as baking soda, to see how temperature affects their solubility.

• Wear chemical splash goggles.
• Handle hot water carefully to avoid burns.
• Use stable graduated cylinders to prevent tipping.

• Does sugar dissolve more in hot water or cold water? (Sugar dissolves more in hot water.)
• Does salt dissolve more in hot water or cold water? (Salt shows little difference between hot and cold water.)
• Why does sugar’s solubility increase more with temperature than salt’s? (Molecular differences cause sugar to interact more strongly with water as temperature rises.)