Solutions, Suspensions Colloids

Solutions Appears to be a single substance

but really two or more substances dissolved in a solvent and evenly distributed

Very small particles that never settle out

Homogeneous

Examples of Solutions Alloys – solid solutions of metals or

non-metals dissolved in metals Iced tea, salt water, soda, gasoline

Solute versus Solvent A solute is the substance in a solution that

gets dissolved A solvent is the substance in a solution

that does the dissolving If something is soluble, the solute can be

dissolved in a particular solvent If something is insoluble, the solute will

not be dissolved in a particular solvent Solutes can be soluble in some solvents

but insoluble in others

Concentration The comparison of solute to solvent When there is not a lot of solute

compared to solvent, the solution is dilute

When there is a lot of solute compared to solvent, the solution is concentrated

Saturated Solutions Saturated solution – contains all of

the solute it can hold at a given temperature. If you add even one more molecule of

the solute, it will fall out of solution and rest on the bottom

Unsaturated Solutions Contains less solute than it can

hold at a given temperature Can add more solute and it wont fall

out of the solution

Supersaturated Solution Solution that holds more than it

usually would at a given temperature

Solubility The amount of solute needed to make a

saturated solution in a given solvent at a given temperature

For solid solute in liquid solvent – solubility rises as temperature rises.

For gas solute in a liquid solvent – solubility lowers as temperature risesex – soda goes flat at warm temperatures

Methods to speed up dissolving Crushing a solute increases the surface area of

the solute allowing more solvent to surround it thus dissolving it faster Ex. Putting butter in macaroni and cheese

Heating a solution increases the energy of the molecules making them move more quickly thus spreading the solute throughout the solvent and speeding up the rate at which the solute dissolves Ex- cooking iced tea

Mixing has the same effect as heating does Ex- making chocolate milk

Suspensions A suspension is a mixture in which

particles of material are dispersed throughout a liquid or gas and are large enough to settle out

The particles are insoluble Heterogeneous mixtures Ex snow globe

Colloids Have properties of both solutions and suspensions Particles in a colloid are much smaller than

particles in a suspension Colloids have the same definition as suspensions

in that a colloid is a mixture in which particles of material are dispersed throughout a liquid or gas, but the particles of a colloid are not large enough to settle out

Particles in a colloid scatter light Ex milk, fog, jello