<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />

# Supersaturated Solutions

## Introduction to a solution that contains more solute than is capable of being dissolved

Estimated1 minsto complete
%
Progress
Practice Supersaturated Solutions

MEMORY METER
This indicates how strong in your memory this concept is
Progress
Estimated1 minsto complete
%
Supersaturated Solutions

Credit: Courtesy of the US Marine Corps
Source: http://commons.wikimedia.org/wiki/File:USMC-20462.jpg

#### How does a hot or a cold pack work?

In the picture above, a thermal pack is applied to the back. Small packs can be used either for heating or cooling, depending on the material used. A heat pack contains a supersaturated solution of material such as sodium acetate. The solution is clear until a small metal trigger is activated. The sodium acetate then crystallizes out of solution and generates heat in the process.

### Supersaturated Solutions

Some solutes, such as sodium acetate, do not recrystallize easily. Suppose an exactly saturated solution of sodium acetate is prepared at 50°C. As it cools back to room temperature, no crystals appear in the solution, even though the solubility of sodium acetate is lower at room temperature. A supersaturated solution is a solution that contains more than the maximum amount of solute that is capable of being dissolved at a given temperature. The recrystallization of the excess dissolved solute in a supersaturated solution can be initiated by the addition of a tiny crystal of solute, called a seed crystal. The seed crystal provides a nucleation site on which the excess dissolved crystals can begin to grow. Recrystallization from a supersaturated solution is typically very fast.

### Summary

• A supersaturated solution can recrystallize when a seed crystal is added to the solution.

### Review

1. How do we know a solution is supersaturated?
2. How can we cause recrystallization of a supersaturated solution?
3. What does the seed crystal do?

### Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes