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What is the Universal Solvent?
Water is the Universal Solvent.
Lots of substances dissolve in water to become (aq) solutions.
Solution
Homogeneous Mixtures composed of at least one solute (what is dissolved) and one solvent (what it is dissolved in)
chemical formula: formula of solute, solvent in parenthesis.
NH3 (aq) - dissolved in water
L2(alc) - dissolved in alcohol
Solutions can be in any state
State | Solvent | Solute |
---|---|---|
Gases (Air) | Nitrogen | - Oxygen - Carbon Dioxide - Inert Gases |
Liquids (Fuel) | Gasoline | - Oil |
Solids (Brass) | Copper | - Zinc |
Solute (What is being dissolved)
Solute Particles can be either Ionic or Molecular Compounds.
Solubility Theory: Like dissolve Like
Ionic Compounds and Polar Molecular Solutes will dissolve in Polar Solvents.
dissolves in water → creating an (aq) solution.
cannot dissolve in Non-Polar Solvents,
Non-Polar Solutes will dissolve in Non-Polar Solvents.
cannot dissolve in Polar Solvents.
Solvation (When a Solute dissolves)
Solvent Particles attract Solute Particles.
causes individual particles to break away from each other
Once particles are separated and surrounded by solvents.
the particles become Solvated.
Factors that affect Rate of Solvation (4 Factors)
Temperature:
temp ↑, rate ↑ (directly proportional)
Particle Size:
particle size ↓ , rate ↑ (inversely proportional)
Agitation (Stirring):
rate ↑
Nature of Solute:
Ionic Compounds and Highly Polar Solutes dissolve faster than Slightly Polar Solutes in Polar Solvents
have stronger attraction → separate out faster
Solubility
the ability of a substance to dissolve in a solvent (usually water).
solubility of Ionic Compounds is determined by using the solubility table
Can be quantified by the concentration of a Saturated Solution.
Solution is considered to be Saturated when no more solute can dissolve in a solvent at a specific temp.
Units for Solubility
%(w/v)
mol/L
Solubility is dependent on temperature.
Temp Value must accompany a Solubility Value.
(what temp does it become soluble in?)
Solubility Values
Every Pure Substance has a unique solubility value.
Salt (NaCl) has a solubility value of 46g/100mL of water
meaning only 46g of salt can be dissolved in water.
if 50g salt were added, 4g would remain as a solid in the solution.
What is the One Major Assumption when using Solubility Values?
Solute is NOT REACTING with the solvent, it is only being dissolved.
Factors that affect Solubility (3 Factors)
Temperature
Pressure
Miscibility
Temperature in Solubility
Solids:
most solids - solubility ↑, temp ↑ (direct)
Liquids:
most liquids - temp has little effect
makes polar solutes more miscible in polar solvents
Gases:
solubility ↓, temp ↑ (inverse)
Pressure in Solubility
Solids:
little effect
Liquids:
little effect
Gases:
solubility ↑, pressure ↑ (direct)
Miscible
Polar Liquids have higher solubility at higher temps, these liquids are known as Miscible.
Miscibility in Solubility
Liquids containing Small Polar Molecules with Hydrogen Bonds → dissolved completely in water, regardless of the quantity mixed.
ethanol will dissolve in water in any proportion with no max concentration!
Liquids that are insoluble in each other are Immiscible.
difference in density → one liquid will form a layer on top of the other
similar densities → one will emulsify in the other
Saturated Solutions
concentration of the dissolved solute is constant. (AT MAX)
no change in observable properties
Saturated Solutions are in a Dynamic Equilibrium.
equal amount of solute in solution crystallizing
equal amount of solute as a solid dissolving in a solution.
Unsaturated
Saturated
Supersaturated
Unsaturated:
less than max amount of solute for given amount of solvent.
can add more solute.
Saturated:
max amount of solute for a given amount of solvent
no more solute dissolves.
Supersaturated:
more than max amount of solute for a given amount of solvent
crystals (solids) may grow as more solute is added.
Hydrates
Substances that have water part of their crystal structure.
Empirical Properties
can be observed by using our five senses
(most often what we see)
Acids Empirical Properties
electrolytic (conductive)
blue litmus → red
react with metals → produce H2(g) bubbles
neutralized by bases
NOT SAFE IN A LAB ENVIRONMENT!
corrosive
sour
Bases Empirical Properties
electrolytic (conductive)
red litmus → blue
neutralized by acids
NOT SAFE IN A LAB ENVIRONMENT!
feel slippery
corrosive
bitter
Neutral Empirical Properties
ionic solute → electrolytic (conductive)
molecular solute → non-electrolytic
no effect on litmus
Electrolytes
compounds that conduct electricity in an (aq) solution or in a molten (liquid) state
able to dissociate in water → carry an electrical charge
includes all soluble ionic, acidic and basic solutions.
Non-Electrolytes
aqueous solutions that do not conduct electricity
unable to dissociate into ions → disperse
includes most molecular compounds.
Exceptions: Molecular Compounds that can be Electrolytic
water
ammonia
Strong Electrolytes
large portion of the solute dissociates and exists as ions
Conductivity:
bulb burns brightly
more bulbs lighting up
higher # reading
Examples:
sodium hydroxide
sodium chloride
hydrochloric acid
Weak Electrolytes
small portion of the solute dissociates and exists as ions
Conductivity:
bulb burns dimly
fewer bulbs lighting up
lower # reading
Examples:
water
acetic acid
ammonia
Diagnostic Test: Acids
Conductivity:
tests (+) → 2+ lights will glow
Litmus:
blue litmus → red
Metal Strip:
metal will dissolve → produces H2(g) bubbles
Diagnostic Test: Bases
Conductivity:
tests (+) → 2+ lights will glow
Litmus:
red litmus → blue
Metal Strip:
no effect
Diagnostic Test: Neutral Ionic
Conductivity:
tests (+) → 2+ lights will glow
Litmus:
no effect
Metal Strip:
no effect
Diagnostic Test: Neutral Molecular
Conductivity:
tests (-) → 0-1 lights will glow
Litmus:
no effect
Metal Strip:
no effect
Arrhenius & Molecular Compounds
neutral particles (non-electrolytes) → solutions cannot conduct electricity
non-electrolytes disperse electrically neutral particles throughout solution.
Disperse Formula:
XY(s,l or g) → XY(aq)
change state to (aq)
ex ) C12H22O11(s) → C12H22 O11(aq)
Arrhenius & Ionic Compounds
when ionic compounds dissolve → ions dissociate (come apart)
positive ions are surrounded by negative ends of polar water molecules
(+) → (-) water
negative ions are surrounded by the positive ends of polar water molecules.
(-) → (+) water
Dissociate Formula:
MX(s) → M+(aq) + X-(aq)
separates into charged ions, changes states
ex ) NaCl(s) → Na+(aq) + Cl-(aq)