CK-12 Physical Science - For Middle School

(Marvins-Underground-K-12) #1

10.2. Solubility and Concentration http://www.ck12.org


10.2 Solubility and Concentration


Lesson Objectives



  • Define solubility, and list factors that affect it.

  • Define concentration, and explain how to calculate it.


Lesson Vocabulary



  • saturated solution

  • solubility

  • unsaturated solution


Introduction


Tanya and Jon want to see if baking soda or sugar dissolves faster in water. Tanya adds 500 g of baking soda to 500
mL of room-temperature water. At the same time, Jon adds 500 g of table sugar to 500 mL of room-temperature
water. Both students start stirring the mixture they made. In less than a minute, all of the sugar in Jon’s mixture has
dissolved. Tanya keeps stirring her mixture of baking soda and water, but after 5 minutes, some of the baking soda
still hasn’t dissolved. Even if Tanya kept stirring her mixture all day, the remaining baking soda would not dissolve.
What explains this result? Read on to find out.


Solubility


Solubilityis the amount of solute that can dissolve in a given amount of solvent at a given temperature. Some
solutes have greater solubility than others in a given solvent. For example, table sugar is much more soluble in water
than is baking soda. You can dissolve much more sugar than baking soda in a given amount of water. Compare the
solubility of these and other solutes inFigure10.2. For a video about solubility, go to this URL: http://www.youtu
be.com/watch?v=IKimraU21ws (10:21).


MEDIA


Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5008
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