The Solution Process Chemistry Mrs. Coyle

Solution A homogeneous mixture. One phase. Stainless Steel (Fe, Cr, Ni)

Solute, Solvent Solute—the substance being dissolved. Example: When you dissolve CuCl2 in water, CuCl2 is the solute. Solvent- the substance that dissolves the solute. Example: water

Aqueous Solution A solution that has water as the solvent. Possible substances that can dissolve in water: Ionic compounds Polar covalent compounds

Solvation The surrounding of solute particles by solvent particles.

Dissociation of Ionic Compounds the process by which an ionic compound separates into its ions as it dissolves.

Dissociation of NaCl in Water

Dissociation of NaCl

Movie Clip- Dissociation of Salt in Water http://www.youtube.com/watch?v=EBfGcTAJF4o

“Like dissolves like” Solvent Solute Is Solution Likely? Polar Yes Nonpolar No

Polar ethanol molecule is dissolved by the polar water molecule Polar ethanol molecule is dissolved by the polar water molecule. Ethanol remains intact.

Will sugar dissolve in water?

Will petroleum dissolve in water?

Oil on water- 2 phases

Will ionic compounds conduct electric current when dissolved in water? Yes Why?

Electrolytes and Non-electrolytes Electrolytes: conduct an electric current when in the molten state or in aqueous solution. Ionic compounds Non-electrolytes do not conduct a current. Usually molecular compounds

Is sugar C6H12O6 electrolyte?

Do all electrolytes conduct electricity to the same degree? Weak electrolytes: partially ionize in water and conduct electricity in solution poorly (ex. Ammonia) Strong electrolytes: fully ionize in water and conduct electricity in solution strongly(ex. NaCl).

Hydrate: A crystalline compound in which the ions are attached to one or more water molecules.

Example: CuSO4•5H2O copper(II) sulfate pentahydrate

Prefixes for naming Hydrates mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa- 8 nona- 9 deca- 10

Analyzing Hydrates Simulation click on the link below: http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/empirical.html

Problem Calculate the percent by mass of water in washing soda (Na2CO3 . 10 H2O) % mass of H2O = MM water x100 % MM Hydrate Answer: 62.9%

Efflorescent Hydrates Hydrates that have high vapor pressures compared to water. When the vapor pressure of the surrounding is lower than the vapor pressure of the hydrate, the hydrate will lose its water; it effloresces.

Hygroscopic Hydrates and Dessicants Hydrates that have a low vapor pressure compared to water. These hydrates can absorb water from the air. These can be used as dessicants (ex. CaSO4).

Deliquescent Materials that absorb so much water that they will become wet (form solutions). Ex. NaOH.

Part II Heterogeneous Aqueous Systems

Colloids and Suspensions Heterogeneous Mixtures

Suspension A mixture whose particles are temporarily suspended in a medium, but eventually settle down. Particle size>100nm Ex: dust in air.

Colloid A mixture whose particles (of size ~1 to ~100nm) are dispersed through a continuous medium. (The word colloid means “glue-like”) Heterogeneous because there are distinct phases. Tyndall Effect: Scattering of light.

Tyndall Effect

Types of Colloids Aerosol: liquid or solid in dispersed in gases (fog, smoke). Foam: gas in liquid (whipped cream). Emulsion: both substances are liquids (mayonnaise). Sol: solid in liquid (jelly)