Solutions, Suspensions and Colloids

Acids, Bases and Salts

SolutionsAll solutions are made of very small particles that do not affect light beams with:Solute – the chemical that is dispersedSolvent – the chemical that causes dispersalExamples: Salt water, Sugar water, vinegar, Coke, Air, Gold jewelry

Properties of Solutions

• Solute is homogeneously dispersed • All properties are the same throughout

solution• Particle size is very small• Gravity does not affected solutions over time• Solute particles can be molecular(as a sugar

solution) or ionic (as a salt solution)• Ionic solutions will conduct electricity

Colloids

• A mixture with small undissolved particles that do not easily settle out.

• Particles are larger than a solution but smaller than a suspension

• Particles are large enough to begin to scatter light (Tyndall Effect)

• Examples: Milk, gelatin, whipped cream, mayonnaise,

Suspensions

• Much larger particles• Often totally blocks transmission of light• Gravity will remove the suspended particles in

time to clear the solvent• Heterogeneous dispersal of suspended

particles• Examples: Pepper, sand or dirt in water

solutions colloids suspensions

< 1 nm > 100 nm

-atoms-small molecules-ions

-aggregates of atoms, molecules or ions-macromolecules (proteins)

-clumps of particles,-mineral grains such as sand

Comparison of Solutions, Colloids, and Suspensions

solutions colloids suspensions

< 1 nm > 100 nm

More Comparison…

Transparent to Opaque

Translucent toOpaque

molecular motionBrownian motion

movement by gravity

coagulation – can settle

never settle

transparent(clear)

solutions colloids suspensions

< 1 nm > 100 nm

-dissolved in water electrolytes

(salts) gases glucose

-plasma proteins albumins globulins fibrinogen

-cellular stuff red blood cells white blood cells platelets

Using whole blood as an example…

Dissolving process in water

Na+

Cl-

1. Overcome attractive forces in solid

2. Hydration of soluteOrientation of water molecules around solute

Pure Water

H20

Non-electrolyte -No dissociation,all molecules in solution. No Ions are present to allow electrons to pass.

no conductivity

Types of solutes

Na+

Cl-

Strong Electrolyte -100% dissociation,all ions in solution

high conductivity

Types of solutes

CH3COOHCH3COO-

H+

Weak Electrolyte -partial dissociation,molecules and ions in solution

slight conductivity

Types of solutes

sugar

Non-electrolyte -No dissociation,all molecules in solution

no conductivity

Solubility of Solutes in Water

Temperature

Solu

bilit

y, g

/100

mL

wat

er Most solids(endothermichydration)

Some solids(exothermichydration)

All gases

How do I get sugar to dissolve faster in my iced tea?

Stir, and stir, and stir

Add sugar to warm tea then add ice

Grind the sugar to a powder

Fresh solvent contact and interaction with solute

Greater surface area, more solute-solvent interaction

Faster rate of dissolution at higher temperature