(POS) Solubility Lesson
Solubility
Have you ever wondered why it is easier to stir sugar into hot tea rather than into iced tea? Or, why no matter how much you shake a jar of oil and vinegar, it always seems to separate? These observations can be explained by a property of solutions known as solubility. In this lesson, you'll learn how molecular structure and binding forces contribute to the solubility properties of various solutions and mixtures.
Let's begin thinking about if salt or sugar dissolves faster in water. To see, you add the same amount of salt and sugar to a half liter of room temperature (20 °C) water in separate glasses. Then you stir 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 you keep stirring the saltwater mixture all day, the remaining salt would not dissolve. Do you know why? The answer is their solubility.
Solubility is the amount of solute that can dissolve in a given amount of solvent at a given temperature. It is important to remember that 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 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 the table below.
| Solute |
Grams of Solute that Will Dissolve in 0.5 L of Water (20 °C) |
|---|---|
| Baking Soda | 48 |
| Epson Salt | 125 |
| Table Salt | 180 |
| Table Sugar | 1000 |
For an explanation of solubility, please watch the video below.
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