CLASSIFYING MIXTURES
Amber Sager
PURPOSE
 To classify mixtures as solutions or colloids using the Tyndall
effect
MATERIALS
 sodium hydrogen carbonate
 cornstarch
 stirring rod
 distilled water (or tap water)
 flashlight
 masking tape
 3 jars with parallel sides
 teaspoon
 cup
PROCEDURE
 In a cup, make a paste by mixing 1/2 teaspoon cornstarch with 4
teaspoons water.
PROCEDURE
 Fill one jar with water. Add one half teaspoon sodium hydrogen
carbonate to a second jar and fill with water. Stir to mix. Add the
cornstarch paste to the third jar and fill with water. Stir to mix.
PROCEDURE
 Turn out the lights in the room. Shine the beam of light from the
flashlight at each of the jars and record your observations
Water
Baking Soda
Corn Starch
CONCLUSION
 Some of the sources of error for this lab would be that I forgot to
use the distilled water so I ended up using that tap water. That might
have effected my results because tap water has certain minerals that
distilled water doesn’t have. I can improve next time by following the
directions completely.
CONCLUSION
 The jars that I could see the light through were the water and
water mixed with baking soda. I believe what made the light visible
was that the mixtures had particles that were too tiny. If it was filtered
I don’t think you would be able to see through it because the water is
what makes it able to see through. If you were to replace the baking
soda with sugar or salt I think it would be the same result because
your salt and sugar are small.
CONCLUSION
 If you were to replace the corn starch with flour or diluted milk it
would again cause the same thing because of the consistency of the
three items. You can distinguish a colloid from a suspension because
you can’t see through a colloid but you can see through a suspension.
CA STATE STANDARD