By: Paige Garcia Mrs. La Salle Chemistry period 3 • To classify mixtures, using the Tyndall effect as solutions or colloids. • • • • • • • • • Baking Soda (sodium hydrogen carbonate) Cornstarch Stirring Rod Tap Water Flashlight Masking Tape 3 Jars (cups) Teaspoon Cup • 1. Mix ½ teaspoon of cornstarch with 4 teaspoons of water in a cup. • 2.Fill jar with water. Add ½ teaspoon of baking soda to 2nd jar and fill with water. Add paste from step 1 to the 3rd jar and fill with water. Then stir/mix. • 3.Turn off lights in room. Shine the flashlight to each jar and record observations. • I did not have time to take pictures of all steps. • The Tyndall effect is the scattering of light by colloid particles or particles in suspension. In this lab the colloid was the jar filled with cornstarch and water which when the light was shined on to it absorbed/ bounced off the particles and scattered. While the jar filled with the baking soda and water was dissolved and clear. A possible source of error from this lab was not having the room completely dark when analyzing the jars with the flashlight. • 1. I was able to see the path of the beam of light through the jar filled with cornstarch and water. • 2. The light beam can be seen because some of the light bounces off the cornstarch particles and is redirected for us to see, because it is a colloid. • 3. If you were to replace baking soda with table salt you wouldn’t be able to see the beam of light because salt dissolves into the solution instead of the particles saying intact. • 4.If you were to replace cornstarch with flour I think you would be able to see the light through it because the light bounces off the particles because it is a colloid. • 5.When a beam of light is passed through a colloid, the path of the light becomes is visible because the particles absorb light and scatter it in all directions. The Tyndall effect is not shown by true solutions because the solute molecules cannot reflect light.