Hot IceWhat’s the Problem with the Solution?

The Scientists of Medaille PresentThe Scientists of Medaille Present

Hot IceWhat’s the Problem with the

Solution?

The Mad Scientists of Medaille Present

The Mad Scientists of Medaille Present

Word

s t

o

Kn

ow • Freeze

• Melt• Solvent• Solute

• Saturated• Supercooled• Exothermic• Nucleation

Freeze

• To turn from a liquid into a solid.

• Water freezes into ice at 0o C or 32o F

Melt• To turn from a solid into a liquid.

• Lead melts at 700o C

• Ice melts at 0o C

SolutionsSATURATED SOLUTION

no more solute dissolves

UNSATURATED SOLUTIONmore solute

dissolves

SUPERSATURATED SOLUTION

becomes unstable, crystals form

Supercooled Liquid

• A liquid is supercooled if it is below its freezing point without becoming solid.

Exoth

erm

ic• An exothermic reaction releases

heat. • It puts out heat

• An endothermic reaction is one that gets cold.

• It takes in heat• Salt and ice

Nu

cle

ati

on • The beginning of a phase

transition.

• 3 phases of matter: Solid, Liquid and Gas.

Today`s Experiment

Making Hot Ice

How

? • Make solution using a special solvent and solute.

• Supercool solution• Provide a nucleation point.

What Should Happen

• Observe phase change

• It will freeze.

• Exothermic: gets hot.

• Sodium Acetate: NaCH3COO

• Used in textile and rubber production

• Vinegar flavoring agent

Solu

te

• Tasteless and odorless

• Many industrial uses

• Common food additive

• Serious property damage

• Injury & death

• Dihydrogen monoxide

Solv

en

t

Lab

Safe

ty• Eye protection

• No loose clothes

• Wash your hands

• Don’t touch your eyes

• No horse play.

Procedure

• 1 l solvent to near boiling.

• Add 800 g of solute.

• Stir until dissolved.

• Add solute until saturated

Procedure Continued

• Add solute →no more will dissolve

• Add solvent → all is dissolved.

Procedure Continued

• Pour into clean container

• Stand until cool

• Pour into small containers for experimentation.

Remember This Guy?• The same

thing is going on with the water as with the sodium acetate!

• The ice in the glass is providing a nucleation point for the water

• Supercooled to below freezing (30o F, or -2o C)

• Nucleation point• Phase change• Exothermic (32o F, or

0o C)

• It’s just harder to do this with water because supercooled water is not as stable as the sodium acetate solution

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