Solutions: More Vocab

Soluble soluble: capable of being dissolved a substance that dissolves in another substance is said to be soluble in that substance

Insoluble a substance that does not dissolve in another substance

solubility: maximum amount substance that dissolves in given amount of another substance LIMITED amount solute that dissolves in given amount solvent affected by temperature and pressure

rate of dissolving is different from amount that will dissolve! rate is how fast amount is how much

factors that affect the rate of dissolving: temperature stirring or agitation amount of surface area of solute amount of solute already dissolved

Dissolving dissolving is physical change

dissolved covalent substances: produce MOLECULES in solution source dissolved covalent substances: produce MOLECULES in solution C6H12O6(s) + H2O(l) C6H12O6(aq)

dissolved ionic substances: produce IONS in solution NaCl(s)+H2O(l)  Na+1(aq) + Cl-1(aq)

Solvation interaction between solvent molecules & solute particles solute particles surrounded by solvent particles during dissolving process solute particles may be: ions polar molecules non-polar molecules solvent molecules may be: polar non-polar

Solvation in different systems.

Hydration describes solvent-solute interaction when solvent is water hydration of chloride ion also called: molecule-ion interaction

Molecule-ion interaction Solute-solvent interaction must be greater than: interaction between solute particles for dissolving to occur

Solubility amount solute dissolved in specific amount solvent at given TEMPERATURE and PRESSURE units: grams solute per 100 grams solvent

Solubility Curves of Selected SOLIDS solubility traces for most solids have (+)’ve slopes; the hotter the solvent, the more solute dissolves

Solubility Curves of Selected GASES solubility traces for all gases have (–)’ve slopes Do you know why most fish prefer cold water?

Vocabulary Interlude miscible: two liquids that WILL MIX together in any amounts water and ethanol are miscible in all proportions immiscible: liquids that will NOT MIX oil and water are immiscible

Oil & H2O are immiscible

Types of Solutions Matter Mixtures Elements Compounds Pure Substances Homogeneous Mixtures = Solutions Heterogeneous Elements Compounds Conduct current Nonconductor

Electricity What do you need to conduct electricity? mobile, positively charged particles!!!!

Vocabulary Interlude electrolyte: non-electrolyte: substance that dissolves in water to form solution that conducts electricity ions present in solution non-electrolyte: substance that dissolves in water to form solution that does not conduct electricity neutral molecules present in solution

electrolyte vs. non-electrolyte Which solution conducts a current?

Dilute vs. Concentrated large amounts of solute present dilute small amounts of solute present

the stronger the color, the more concentrated the solution Which solution is most dilute? most concentrated? How can you tell? the stronger the color, the more concentrated the solution

to dilute a solution: add MORE solvent

Which solution is more concentrated? More dilute? What can you say about the # of solute particles in pictures b and c? the # is the same!

Unsaturated Solution less than maximum amount solute that will dissolve at given T and P

Saturated Solution no more solute will dissolve at given T & P solubility = amount solute required to form saturated solution

The solution is saturated when the solute stops dissolving 

Dynamic Equilibrium in Saturated Solution microscopic level: rate dissolving = rate recrystallization macroscopic level: no apparent change

Supersaturated Solution contains more solute than saturated solution VERY unstable have to be clever to make these (need to use heat)

Testing for saturation: add additional crystal of solute into solution and see what happens

3 possible results: unsaturated solution saturated solution crystal dissolves: crystal sinks to bottom of solution: Bam! Suddenly have lots of solid solute in beaker: saturated solution supersaturated solution

What kind of solution was this?

How do terms saturated, unsaturated & supersaturated fit in with the solubility curves?

saturated solns: any point on trace line (max solute dissolved) supersaturated solns: all points above trace lines (more than max) unsaturated solutions: all points below trace lines (less than max)

A B C D characterize points A, B, C, D with respect to KNO3 trace line (dilute, concentrated, saturated, unsaturated, or supersaturated) A B A,C = concentrated & supersaturated B=concentrated & saturated C D D = dilute & unsaturated

Solubility Graphs traces: have positive or negative slopes most solids have positive slope the hotter the water, the more solute dissolves The colder the water, the less solute dissolves all gases have negative slope the hotter the water, the less gas dissolves The colder the water, the more gas dissolves

Summary of Dissolving occurs at surface of solid interaction: between solute & solvent interaction called “solvation” interaction called “hydration” (if solvent is H2O) involves: change in energy