Surface Area and Solubility: Sweet Solutions (page 2)

The dissolving medium in a solution is called a solvent, and the substance being dissolved is called the solute. Several factors can influence the rate at which a solute dissolves in a solvent. For example, increasing the surface area of a solute speeds dissolving. Crushing or pulverizing a large solid into smaller pieces exposes more surface area to the solvent. In this activity you will see how surface area affects the rate at which candy dissolves in your mouth.

Materials

Three after-dinner mints (small size)

Clock or watch with a second hand

Paper towel

Activity

1. Place an after-dinner mint in your mouth and hold it there without chewing or moving the mint around. Use the second hand of the clock to time how long it takes the mint to completely dissolve. Record the time.
2. Place a second mint in your mouth. This time move your tongue around, but do not chew the mint. Note how long it takes for the mint to dissolve.
3. Place a third mint in your mouth and chew it. Note how long it takes the mint to dissolve.

Follow-Up Questions

1. How long did it take each mint to dissolve?
2. Scientifically explain your results. Use the following words in your explanation: surface area, agitation, chewing, solvent, solute, and solution.

Answers

1. Answers will vary, but the mint that was chewed should have dissolved faster than the mint moved around with the tongue. The mint moved with the tongue should have dissolved faster than the mint just held in the mouth.
2. Answers will vary, but students should indicate that agitation and chewing increase surface area of the mints. The solute was the mint, and the solvent was saliva in the mouth. The combination of the two formed a solution.

Extension

Do some research and list all the factors that affect the rate at which a solid dissolves in a liquid. Also research some factors that affect the rate at which a gas dissolves in a liquid.