Is it easier to dissolve sugar in hot tea, or cold tea? Why do you think this is?

What does it mean, to “dissolve”?

Setup Cornell Notes, Titled: “Solutions and Solubility”

Solutions and Solubility

5-10-11Cornell NotesGuided WS

Key Definitions

Solution - a uniform mixture that contains one substance dissolved in another substance

Dissolve - to cause to disappear or vanish

Solvent - The substance that dissolves the solute in a solution. Also, the most plentiful substance in a solution.

Solutes - One or more substances dissolved in a solution.

SOLUTE SOLVENT

What happens when something dissolves?Particles of a solute become surrounded by

particles of a solvent

Solubility

The ability of a solute to dissolve in a solvent.

MORE COLLISIONS BETWEEN SOLVENT AND SOLUTE = HIGHER SOLUBILITY

Factors that affect solubility: How do we dissolve things?MORE COLLISIONS BETWEEN SOLVENT AND

SOLUTE = HIGHER SOLUBILITY

Agitation: shaking or mixing Surface area: the amount of substance touching

the solvent Temperature: makes molecules move

Levels of SaturationHow much solute is dissolved in a

solution

Unsaturated: if you were to add more solute, it would still dissolve

Saturated: you have dissolved all the solute you can

Supersaturated: There is more solute dissolved than is possible (it starts precipitating back into a solid)

Common terms

Concentrated – strong, lots of solute compared to solvent

Diluted – weak, very little solute compared to solvent

Solubility Curve A picture of how soluble a compound is Solubility vs. Temperature: Measures how

much solute dissolves in 100 mL of water at different temperatures

Temperature (˚C)

Maximum amount of solute that can dissolve in the solvent at that temperature

Solubility (g solute in 100 mL of

H2O)

What can we do with a solubility curve?

1: Identify which compounds are more soluble at a specific temperature

The higher the curve, the more soluble!

At 100˚C, which is more soluble: KBr or NaCl?

KBr is more soluble!

What can we do with a solubility curve?

2. We can determine the level of saturation!

Solubility (g solute in 100 mL of

H2O)

Temperature (˚C)

Points where a solution is SATURATED

UNSATURATED

Below the curve

SUPERSATURATED

Above the curve

Example

Solubility Curve of KNO3

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100

Temperature (˚C)

So

lub

ility

(g

of

so

lute

in 1

00

mL

of

wa

ter)

If we dissolve 100 g of KNO3 in 100 mL of water at 30˚C, what is the level of saturation of the solution?

SUPERSATURATED

What can we do with a solubility curve?

3. Determine how much solute can dissolve in a solution at a specific temperature

Solubility Curve of KNO3

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100

Temperature (˚C)

So

lub

ility

(g

of

so

lute

in 1

00

mL

of

wa

ter)

At 60˚C, how many grams of KNO3 can we dissolve in 100 mL of water?

100 g of KNO3 can

be dissolved!

What would happen if we dissolved 100g of KNO3 to saturation at 60°C, then lower the temperature to 20°C?

Solubility Curve of KNO3

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100

Temperature (˚C)

Solub

ility (

g of s

olute

in 10

0 mL o

f wa

ter)

Start Worksheet!