Solutions and Solubility

Solutions

• formed when substances ____________ in other _____________

• _______________ mixtures• _______________ phase• remain _______________;

particles do not _______________ out

• cannot be separated by _______________

dissolve

substances

homogeneous

singlemixed

settle

filtration

Parts of a Solution– solvent:

• present in _______________ amount• ____________ the ____________ to make the

solution

– solute:• present in _______________ amount

• _______________ in the ______________

larger

dissolves solute

lesser

dissolved solvent

LIQUID SOLUTIONS

• liquid solvent in which a gas , solid , or liquid is dissolved

• gas dissolved in liquid:– ex. carbonated beverage

• liquid in liquid:– ex. antifreeze in water

• miscible: the two liquids mix• immiscible: the two liquids don’t mix• solid dissolved in a liquid:

– ex. salt water• Aqueous: water is the solvent• Tincture: alcohol is the solvent

SOLID SOLUTIONS:• alloys: solid mixtures of metals

• (brass is a mixture of copper and zinc)

GAS SOLUTIONS:

• gases dissolved in each other

(air is most common example)

Suspension

• a heterogeneous mixture• Particles in the suspension are thousands of

times larger than molecules and atoms (ions)• Particles will settle out upon standing• can be separated by filtration

• exhibit the Tyndall Effect --the scattering of light in all directions

Tyndall Effect

Glass on left has colloidial silver, while the glass on the right does not

Colloid

particles are medium in size between those of suspensions and true solutions

• particles do not settle out upon standing

• can not be separated by filtration

• exhibit the Tyndall Effect

Emulsion

• colloidial dispersion of liquids in liquids

• emulsifying agent is necessary for maintaining stability (soap is an example)

• Electrolyte: dissolves in water to form a solution that conducts electricity

• Nonelectrolyte: dissolves in water to form a solution that does NOT conduct electricity

Factors Affecting the Rate of Solution

• 1) Surface Area : – increasing the surface area of the solute by crushing

speeds up dissolving by increasing the number of collisions between the solvent and the solute surface.

• 2) Agitation:– stirring or shaking helps to disperse solute particles,

increasing the number of collisions between the solvent and the solute surface.

• 3) Heating:– increases the average kinetic energy of the solvent

molecules so that collisions between the solvent molecules and the solute are more frequent

Solute/Solvent Amounts• Saturated: solution containing all the dissolved

solute possible at given conditions of temperature and pressure.

• Unsaturated: solution containing less dissolved solute than the maximum amount that can be dissolved at given conditions of temperature and pressure.

• Supersaturated: unusual solution containing more dissolved solute than is normally possible at given conditions of temperature and pressure.

Solubility• A measure of how much solute can dissolve in a

given amount of solvent at a specific temperature.

– Dilute Solution: The amount of solute dissolved is small in relation to the amount of solvent present.

– Concentrated Solution: The amount of solute dissolved is large in relation to the amount of solvent

– present.

Solubility Rules 1. Salts containing Group I elements are soluble (Li+, Na+, K+, Cs+, Rb+). Exceptions to this rule are

rare. Salts containing the ammonium ion (NH4+) are also soluble.

2. Salts containing nitrate ion (NO3-) are generally soluble.

3. Salts containing Cl -, Br -, I - are generally soluble. Important exceptions to this rule are halide salts of Ag+, Pb2+, and (Hg2)2+. Thus, AgCl, PbBr2, and Hg2Cl2 are all insoluble.

4. Most silver salts are insoluble. AgNO3 and Ag(C2H3O2) are common soluble salts of silver; virtually anything else is insoluble.

5. Most sulfate salts are soluble. Important exceptions to this rule include BaSO4, PbSO4, Ag2SO4 and SrSO4 .

6. Most hydroxide salts are only slightly soluble. Hydroxide salts of Group I elements are soluble. Hydroxide salts of Group II elements (Ca, Sr, and Ba) are slightly soluble. Hydroxide salts of transition metals and Al3+ are insoluble. Thus, Fe(OH)3, Al(OH)3, Co(OH)2 are not soluble.

7. Most sulfides of transition metals are highly insoluble. Thus, CdS, FeS, ZnS, Ag2S are all insoluble. Arsenic, antimony, bismuth, and lead sulfides are also insoluble.

8. Carbonates are frequently insoluble. Group II carbonates (Ca, Sr, and Ba) are insoluble. Some other insoluble carbonates include FeCO3 and PbCO3.

9. Chromates are frequently insoluble. Examples: PbCrO4, BaCrO4

10. Phosphates are frequently insoluble. Examples: Ca3(PO4)2, Ag2PO4

11. Fluorides are frequently insoluble. Examples: BaF2, MgF2 PbF2.