http://www.ck12.org Chapter 3. Chemical Interactions
3.49 Solubility
- Define solubility.
- Describe how temperature and pressure affect solubility.
Rhonda wanted to see if salt or sugar dissolves faster in water. She added the same amount of salt and sugar to a
half liter of room temperature (20 °C) water in separate glasses. Then she stirred both mixtures. All of the sugar
dissolved in less than a minute, but after 5 minutes of stirring, some of the salt still hadn’t dissolved. Even if she had
kept stirring the saltwater mixture all day, the remaining salt would not dissolve. Do you know why? The answer is
their solubility.
What Is Solubility?
Solubilityis the amount of solute that can dissolve in a given amount of solvent at a given temperature. In a solution,
the solute is the substance that dissolves, and the solvent is the substance that does the dissolving. For a given solvent,
some solutes have greater solubility than others. For example, sugar is much more soluble in water than is salt. But
even sugar has an upper limit on how much can dissolve. In a half liter of 20 °C water, the maximum amount is 1000
grams. If you add more sugar than this, the extra sugar won’t dissolve. You can compare the solubility of sugar, salt,
and some other solutes in theTable3.11. For a video about solubility, go to this URL: http://www.youtube.com/w
atch?v=IKimraU21ws.
TABLE3.11:Solubility of Some Common Solutes in Water
Solute Grams of Solute that Will Dissolve in 0.5 L of Water
(20 °C)
Baking Soda 48
Epsom salt 125