This time of year, many families in the U.S. end up with a whole haul of Halloween candy. Since part of scientific investigation involves looking at things in new ways, let’s do some Halloween candy science! This year, instead of eating all that candy, use some of those sweet treats in an easy science experiment.
Liquids that can dissolve solids are called solvents. Things dissolved in a solvent are called solutes. In this experiment, you’ll use a solvent (water) to dissolve the colored coating on candy (solute).
1. Fill the petri dish with enough cold water to fully cover one M&Ms or Skittles.
2. Carefully drop the candy in being sure not to disrupt the water too much. If you can, drop the candy so it lands with its letter facing up.
3. Start your stopwatch and notice how the candy looks after 30-second intervals.
4. Write down or draw your results.
5. Repeat the experiment with hot water.
Water is often called the universal solvent because, given enough time, it will dissolve just about anything. What happened when you used hot water versus cold water in the experiment? You probably found that hot water dissolved the candy coating faster. That’s because the molecules in hot water move faster than those in cold water. Since faster-moving molecules have more energy, they can dissolve the solute more quickly.
For further study, try using different candies and/or different solvents, like milk, saltwater, or vinegar. How do your results change? What about if you stir your solvent after you drop the candy in? How does agitation affect your results?
Bonus:
If you dropped your candy very carefully and didn’t disturb the water afterward, you may have noticed the white “M” or “S” floating in the water. That’s because the ink used to stamp the letter on the candy is not water-soluble. So although it’s safe to eat, it’s a solute that doesn’t dissolve in water.