How much can dissolve?

How much can dissolve?

If you continue adding sugar to lemonade, eventually the point is reached when no more sugar dissolves and the excess granules sink to the bottom of the glass.

Solubility (sol yuh BIH luh tee) is the maximum amount of a solute that can be dissolved in a given amount of solvent at a given temperature.

Comparing Solubilities

The amount of a substance that can dissolve in a solvent depends on the nature of these substances.

In one beaker, 1 g of solute A dissolves completely, but additional solute does not dissolve and falls to the bottom of the beaker

Comparing Solubilities

1 g of solute B dissolves completely, and two more grams also dissolve before solute begins to fall to the bottom.

If the temperature of the water is the same in both beakers; you can conclude that substance B is more soluble than substance A.

Concentrations

A concentrated solution is one in which a large amount of solute is dissolved in the solvent.

A dilute solution is one that has a small amount of solute in the solvent.

Types of Solutions–Saturated

A saturated solution is a solution that contains all the solute it can hold at a given temperature.

An unsaturated solution is any solution that can dissolve more solute at a given temperature.

Each time a saturated solution is heated to a higher temperature, it becomes unsaturated.

Saturation

Generally, as the temperature of a liquid solvent increases, the amount of solid solute that can dissolve in it also increases. This table shows the amounts of a few solutes that can dissolve in 100 g of water at different temperatures, forming saturated solutions.

Solubility Curve

Each line on the graph is called a solubility curve for a particular substance.

You can use a solubility curve to figure out how much solute will dissolve at any temperature given on the graph.

Supersaturated Solutions

A supersaturated solution is one that contains more solute than a saturated solution at the same temperature.

Supersaturated solutions are unstable.

Supersaturated Sodium acetate

For example, if a seed crystal of sodium acetate is dropped into the supersaturated solution, excess sodium acetate crystallizes out

Energy Flow

As the supersaturated solution of sodium acetate crystallizes, the solution becomes hot.

Energy is given off as new bonds form between the ions and the water molecules

Energy Flow

Another result of solution energy is to reduce the temperature of the solution.

Some substances, such as ammonium nitrate, must draw energy from the surroundings to dissolve.

This is what happens when a cold pack is activated to treat minor injuries or to reduce swelling.