Chapter 4: Solutions Flashcards
Compound of which there is MORE is called a ______ and the compound of which is LESS is called _______.
When neither compound predominates, BOTH compounds are referred to as ________.
Solvent; Solute
Solvents
3 Types of solutions
1) Ideal solutions - made from compounds that have similar properties (meaning compounds can be interchanged within the solution w/o changing spatial arrangement of the molecules or intermolecular attractions); Example: Benzene in toluene
2) Ideally dilute solutions - solute molecules are completely separated by solvent molecules so they have NO interaction with each other.
3) Nonideal solutions - violate both conditions
Example of Colloid
Hemoglobin
Colloidal system can be any combination of phases except for…
Gas in gas
Example of colloidal systems
Aerosol - LIQUID or SOLID particles in a gas like fog/smoke
Foam - GAS particles in a LIQUID (like whipped cream)
Emulsion - LIQUID particles in a LIQUID or solid like milk or butter
Sol - SOLID particles in LIQUID like paint
Colloid particles may be ATTRACTED (_________) or REPELLED (________) by their dispersion medium.
Lyophilic; lypophobic
Lypophobic colloids form when amphipathic (hydrophilic and hydrophobic parts) or charged particles ________ to the surface of the colloidal particles which stabilizes them in the dispersion medium.
Absorb
General rule for dissolution (dissolving) is…
‘Likes dissolve likes’
These molecules are held together by STRONG intermolecular bonds formed by the attraction b/n their __________ charged ends.
These molecules are held together by WEAK intermolecular bonds resulting from instantaneous _________ moments.
These forces are called….
Highly polar molecules; partially charged
Nonpolar molecules; dipole
London dispersion forces
A ________ solute interacts with a _________ solvent by tearing __________ bonds apart and forming ___________ bonds.
Polar; polar
Solvent-solvent; solvent-solute
No polar solvent can tear apart a WEAK bond of a _________
Nonpolar solvent
Ionic compounds are dissolved by ….
Polar substances
Process of Solvation
When ionic compounds dissolve, they break apart into their respective cations and anions and are surrounded by OPPOSITELY charged ends of the POLAR SOLVENT.
When water molecules surround individual ions pointing their positive hydrogens at the anions (-) & their negative oxygens towards cations (+)
When several molecules attach to one end of an ionic compound, they’re able to overcome the strong ionic bond, and break the compound. The water molecules then surround ion. In water this process is called ….
Hydration
Something that’s hydrated is …
Define hydration number
An aqueous phase
Number of water molecules needed to surround an ion that varies according to the size & charge of the ion. *This # is commonly 4 or 6
Compound that forms ions in an aqueous solution is called an …
STRONG electrolytes
WEAK electrolytes
Electrolyte
Create solutions which CONDUCT ELECTRICITY well and CONTAIN MANY IONS.
Compounds which form FEW IONS in solution
- Nitrite
- Nitrate
- Sulfite
- Sulfate
- Hydrochlorite
- Chlorite
- Chlorate
- Perchlorate
- Bicarbonate
- Phosphate
- NO2-
- NO3-
- SO3^2-
- ClO-
- ClO2-
- ClO3-
- ClO4-
- CO3^2-
- HCO3^-
- PO4^3-
Fun fact: what is “HYPONATREMIA”
What are NORMAL sodium levels?
What low sodium levels due to drinking too much water can be critical or even lead to death?
When sodium levels become too low (reduced sodium levels) as a result of drinking too much water
135mM-145mM
125-120mM or lower
5 Ways to measure concentration
1) Molarity (M): mols of compound/ vol of solution (unit: mol/vol)
2) Molality (m): mols of solute/ kg of solvent (unit: mol/kg)
3) Mole Fraction (X): mols of compound/ total moles of all species in sol’n (units: NONE)
4) Mass percentage: 100 x’s the ratio of the mass of the solute/ total mass of solution
5) Parts per million (ppm): 10^6 x’s the ratio of the mass of solute/ total mass of solution
Define a solution
Homogenous mixture of 2 or more compounds in a solid, liquid, or gas
Example: Brass
A solid solution of zinc and copper
Grams / mw =
Moles
1 atm =
760 torr
Formation of a solution is what type of reaction?
Physical
Physical reactions involve 3 steps:
1) Breaking the intermolecular bonds between the solute molecules
2) Breaking the intermolecular bonds between the solvent molecules
3) Forming of intermolecular bonds between the solvent and the solute molecules
Entropy INCREASES for _____ & _____ dissolving in _______.
Entropy usually DECREASES for ________ dissolving in _______.
Solid and liquids; liquids
Gases; liquids
If the overall reaction RELEASES energy (exothermic) , the new intermolecular bonds are ________ and intermolecular attractions within the solution are STRONGER than the intermolecular attractions with the PURE substance.
Less energy in the system means what?
If the OVERALL reaction ABSORBS energy (endothermic) then ….
MORE stable
A MORE STABLE system
The REVERSE is TRUE
Overall Change in energy of the reaction is = to the change in ENTHALPY and is called ….
A NEGATIVE heat of solution results in
A POSITIVE heat of solution results in
The heat solution (delta)Hsol
STRONGER intermolecular bonds
WEAKER intermolecular bonds
Since COMBINED mixture is MORE DISORDERED than the separated pure substances, the formation of the solution involves a what kind of entropy?
Exception to increased entropy rule is what?
Increased
When a gas dissolves in a liquid or solid - this allows for the entropy change to be NEGATIVE
When a liquid or solid dissolves into one another the entropy does what?
Increase entropy
-(delta)G indicates what type of reaction?
When a LIQUID or SOLID dissolves in a LIQUID, (delta)S (entropy) is usually what? Therefore entropy usually does what?
Spontaneous
Positive; FAVORS spontaneous solution FORMATION
Vapor pressure of liquid
Vapor pressure of the compound
Pressure created by the molecules in the open space
Equilibrium b/n liquid & gas phases of compound occurs when molecules move from liquid to gas (L➡️G) as quick as G⬅️L . Partial pressure of the compound necessary to create EQUILIBRIUM is VP OF COMPOUND
When a fluid moves what happens to the partial pressure?
The partial pressure of WATER VAPOR DECREASES!!
Partial pressure of water vapor is LOWER than the vapor pressure of water at that temp, and # of water molecules leaving is ______ than the # of water molecules entering the water. Which means the water is doing what?
Greater
Evaporating
What causes a compound to boil??
Vapor Pressure = local atmospheric pressure
What is atmospheric pressure?
The sum of ALL partial pressures in the air above the liquid
Define MELTING POINT
Temperature of at which the VP of the SOLID is = VP of LIQUID
What is a NONVOLATILE SOLUTE
What is a VOLATILE SOLUTE
A solute with NO VP
A solute with VP
What’s an ideal solution
Where a solute and solvent have similar properties
Some molecules of a volatile solute escape from solution & contribute to …
VP
What is solubility?
A solutes’s tendency to dissolve in a solvent
On MCAT: A solute will mostly be a SALT and the SOLVENT will be WATER
Dissolved molecules of SALT reattach to what?
The SURFACE of the SALT CRYSTAL
What is PRECIPITATION?
INITIALLY precipitation takes place at a _______ rate than dissolution
The reverse reaction of a dissolving salt
SLOWER
As salt DISSOLVES, the CONCENTRATION of salt _____, the rate of DISSOLUTION and PRECIPITATION _______.
BUILDS
EQUILIBRATE
Dissolution = precipitation, the solution is what?
When Saturated, the concentration of dissolved salt reaches a ______ in a saturated solution.
SATURATED
Is the crystallization of salts endothermic/exothermic?
Exothermic
Solubility is….
Solubility depends upon what?
The maximum # of moles of the solute that can dissolve in solution
Temperature & ions in a solution
Solubility Product changes only with what?
Temperature
Spector Ion
Common Ion Effect
Ions that have NO effect on EQUILIBRIUM (ex. Sodium ions: Na+)
Ions that DO affect the EQUILIBRIUM (F-) b/c it involves AN ION COMMON TO AN ION IN EQUILIBRIUM
Le Chatalier’s Principle
The ADDITION of a COMMON ION will push the equilibrium In a direction which tends to REDUCE the concentration of that ion
As temp _________, salt _______.
Increases; increases
