unit 8 - solutions Flashcards
solution
A homogeneous mixture of two
or more substances
solutions contain…
particles of one substance that are uniformly spread out in another substance
ex: C6H12O6 (aq)
parts of a solution
solute and solvent
solute
the substance being dissolved
solvent
the substance that dissolves the solute
solution types - aqueous
water is the solvent
ex: NaCl (aq)
solute (NaCl), solvent (water)
solution types - non aqueous
water is not the solvent
solution types - tincture
alcohol is the solvent
ex: tincture of iodine
contains solute (I2), solvent (alcohol)
solution characteristics
1) Clear or transparent- colorless or colored
2) Particles:
a. Are evenly distributed
(Solutions are homogeneous)
b. Do not settle out on standing
(particles dissolved stay dissolved)
c. Can not be separated by filtration
3) Variable Composition- A solution is a type of mixture, not a pure substance (compound)
solubility
the amount of a solute to dissolve in a certain amount of solvent
soluble
materials with a high degree of solubility (a lot dissolves)
insoluble
materials with a low degree of solubility (little dissolves)
factors that affect solubility: TEMPERATURE (Table G)
1) TEMPERATURE: (Table G)
- As temp increases solids become more soluble
- As temp increases gases become less soluble in water
factors that affect solubility: pressure
2) PRESSURE:
- Pressure has little or no affect on the solubility of solid or liquid solutes
- As pressure increases gases become more soluble in liquids
factors that affect solubility: type of solvent/solute
3) Type of Solute/Type of Solvent:
- “Like Dissolves Like”
- Polar Solutes dissolve in Polar solvents
- Non-Polar solute dissolve in non-polar solvents.
- Ionic Substances dissolve in Polar
solvents (salts in water)
rate of solute dissolving
how fast a solute dissolves depends on frequency of interactions between solute and solvent
factors that affect rate of solute dissolving
1) temperature - greater KE = more interactions
2) stirring - more interactions
3) surface area - grinding and chopping solute into pieces increases surface exposure and more interaction with solvent
double replacement reactions and table F
- Double Replacement Reactions:
Two compounds that react and produce a precipitate. Precipitate is the INsoluble Product! - Ex: Silver Nitrate (aq) + Sodium Chloride (s)
: AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3(aq)
three degrees of saturation
- saturation solution
- unsaturated solutions
- supersaturated solution
saturated solutions
solution which contains the maximum amount of solute that can dissolve in a given amount of solvent at a certain temp.
- point is given on the curve
unsaturated solutions
solution that contains less than the maximum amount of solute that can dissolve at a certain temperature in a given amount of solvent
- point given is below the curve
supersaturated solution
Solution that contains more than the maximum amount of solute than can dissolve (unstable), at a
certain temperature in a certain amount of solvent
- point given is above the curve
measuring concentration by percent
% By Mass = mass of solute/mass of solution x 100
% By Volume = volume of solute/volume of solution x 100
1 PPM
= .0001%
PPM
expresses concentration as the mass of the solute in given amount of solution
PPM = mass solute/mass solution x 1,000,000
evaporation
molecules on the surface of a liquid gain enough KE to break from the liquid and enter the gas phase
ex: water on the floor or open container evaporates
boiling
liquid turns to a gas at any point in the container (not just the surface)
vapor
another word for gas phase
vapor pressure
the pressure that gas particles exert due to collisions above surface of a liquid
vapor pressures varies directly with…
TEMPERATURE regardless of the volume
boiling point
Temperature at which the Vapor pressure is equal to Atmospheric Pressure
*At standard pressure - Normal Boiling Point
*low atmospheric pressure - above sea level
*high atmospheric pressure- below sea level
normal boiling point
temperature at which the vapor pressure exerted by the liquid is equal to Standard Atmospheric Pressure
1 atm, 101.3 Kpa, 760 torr or mmHg
temperature and vapor pressure
as temperature increases so does the vapor pressure of a liquid
table H - remember boiling point
the temperature at which the vapor pressure equals 101.3 kPa
diluted solution
solution in which a small amount of solute in a given amount of water
less solute, more water
concentrated solution
solution which a large amount of solute in a given amount of water
more solute, less water
how do we build a solution
1) put salt in flask
2) add total amt of H2O needed in the problem
molarity
the concentration of a solution in moles of solute per liter of solution
to get L from mL
do mL/1000
as molarity increases, what happens to solution concentration
solution is more concentrated
how can we change the concentration (molarity) of a solution by perfoming a dilution
add water to change a higher concentration to a lower concentration
moles of a substance before dilution are …
equal to the moles of a substance after dilution
steps to performing a dilution
- find V1
- fint amount of H2O to dilute (V2-V1 = amt of water)
- put water into flask first, then add concentrated soution
colligative properties
when you take a pure substance, (ex. water), and add any other substance to it, you affect the original substance’s boiling point and freezing point
concentration of dissolved particles impacts the
boiling point and freezing point of a substance
as concentration increases
the more moles of particles of the solute exist
(remember we measure concentration in (M) molarity)
the greater the concentration or more solute particles, original substance will have its freezing and boiling point…
boiling point increased, freezing point decreased
no matter what is added to a substance, the response will always be the
SAME
colligative properties conclusions: boiling point…? why?
increases
It takes a higher temp (greater Kinetic Energy) for the
appropriate collisions to occur between the gas particles in order to break intermolecular bonds
colligative properties conclusions: freezing point…? why?
decreases
It takes a lower temp (lower KE) for all the liquid particles to come together to form intermolecular bonds and become a solid.
do ionic substances dissociate into +/- ions?
YES
do covalent substances (molecules) dissociate into +/- ions?
NO
which will always produce more moles of particles compared to the other
IONIC substances will always produce MORE moles of particles compared to COVALENT substances
Ex. 1 Mole NaCl → 1 mol Na+ + 1 mol Cl-
(total is 2 mol of particles)
Ex. 1 Mole C6H12O6 → 1 mol C6H12O6
the higher the boiling point, the ____ the substances vapor pressure
lower
the lower the boiling point, the _____ the substances vapor pressure
higher
