

A mixture is 2 or more substances that are combined together that can be separated by physical means (not chemically bonded together)



Heterogeneous mixtures – unevenly mixed mixtures, “different” composition throughout



Homogeneous mixtures – evenly mixed mixtures, “same” composition throughout



Which type of mixture are solutions?



Homogenous mixtures



Solutions have the same

composition

,

color

, and

density

throughout them



We call solutions the “

best mixed mixtures

”



If a solution is made from a substance dissolved in water, it is called an

aqueous solution



To create a solution, one substance must dissolve in another substance



Solute



– the substance being dissolved When solids or gases are dissolved in liquids, they are considered to be the solutes



Solvent



– the substance that does the dissolving When a liquid dissolves another liquid, the liquid that has the largest amount is considered to be the solvent As a general rule of thumb, there is LESS solute and MORE solvent in a solution



Solutions do not always involve a solid or gas dissolving in a liquid



Solid dissolved in solid



i.e. Alloys - brass (Melted metal solute mixed with melted metal solvent and cooled)



Gas dissolved in gas



i.e. air (78% nitrogen, 21% oxygen, 1% other gases)



Liquids dissolved in gas



i.e. clouds



Gas dissolved in solid



i.e. marshmallows



For each example, identify the solute and the solvent:



Kool-Aid

  sugar/ Kool-Aid powder water 

Sterling Silver (92.5% silver, 7.5% copper)

  copper silver 

Styrofoam

 

Solute: _____________________

foam (solid) 

Mountain Dew

  sugar, carbon dioxide (gas) water

 1. Moving solvent molecules cluster around the solute  They are attracted to each other because they have opposite charges (like a magnet)  2. The solvent molecules pull the solute molecules into the solution  3. The solvent and solute molecules spread out to form a homogeneous mixture  Dissolving Animation

 What can you do to increase the rate at which solutes dissolve in solvents?

  

Stir it!

 By stirring, you are bringing more solvent in contact with the solutes, which cause the particles to dissolve more quickly

Decrease crystal size

 If you make larger solutes smaller, you are increasing the surface area of the crystals which allows the solvent to surround it more easily

Increase temperature

 Increasing the temperature speeds up the movement of the particles which causes more of the solvent particles to bump into the solute particles Review Song: http://www.youtube.com/w atch?v=3G472AA3SEs