Solutions and Colloids Flashcards
If a mixture is uniform throughout at the molecular level
Homogeneous mixture or solution
If can easily distinguish between the two components; the mixing does not occur at the molecular level
Heterogeneous mixture
Homogeneous mixtures of solids
Alloys
Five common types of solutions
Carbonated water, wine, salt water, air, 14-carat gold
When a solution consists of a solid or a gas dissolved in a liquid, the liquid is called the
Solvent
When a solution consists of a solid or a gas dissolved in a liquid, the solid or gas is called the
Solute
Properties of solutions
- The distribution of particles in a solution is uniform.
- The components of a solution do not separate on standing.
- A solution cannot be separated into its components by filtration.
- For any given solute and solvent, it is possible to make solutions of many different compositions.
- Solutions are almost always transparent.
- Solutions can be separated into pure components.
The ______ of a solid in a liquid is the maximum amount of the solid that will dissolve in a given amount of a particular solvent at a given temperature.
Solubility
Some solids have a very low solubility in a particular solvent; we often call these solids
Insoluble
Others have a much higher solubility; we call these
Soluble
refer to a liquid dissolving in a liquid.
Miscible
When a solvent contains all the solute it can hold at a given temperature, we call the solution
Saturated
Any solution containing a lesser amount of solute is
Unsaturated
contains more solute in the solvent than it can normally hold at a given temperature under equilibrium conditions
Supersaturated
the positive end of the dipole of one molecule attracts the negative end of the dipole of the other molecule
Polar compounds
For most solids and liquids that dissolve in liquids, the rule is that
solubility increases with increasing temperature
Another way to crystallize the excess solute is to add a crystal of the solute, a process called
Seeding
For gases, solubility in liquids almost
always decreases with increasing temperature
The higher the pressure, the greater the solubility of a gas in a liquid.
Henry’s Law
We can express the amount of a solute dissolved in a given quantity of solvent
Concentration
Chemists represent percent concentration in three ways.
- Weight/volume
- Weight/weight
- Volume/volume
Is not used for weight/weight solution
Volumetric flask
Is not used for weight/weight solution
Volumetric flask
is used only for solutions of liquids in liquids—most notably, alcoholic beverages.
Volume/volume
is defined as the number of moles of solute dissolved in 1 L of solution.
Molarity
is the liquid part of the blood that remains after removal of the cellular particulates and fibrinogen.
Blood serum
Water covers about ____ of the Earth’s surface in the form of oceans, ice caps, glaciers, lakes, and rivers.
75%
The human body is about ___ water
60%
the surrounding shell of solvent molecules—acts as a cushion. It prevents a solvated anion from colliding directly with a solvated cation, thereby keeping the solvated ions in solution.
Solvation layer
The attraction between ions and water molecules is so strong in some cases that the water molecules are an integral part of the crystal structure of the solids. Water molecules in a crystal are called
Water hydration
The substances that contain water in their crystals are themselves called
Hydrates
The crystal without its water is called
Anhydrous
some anhydrous crystals become hydrated upon standing in air. Crystals that do so are called
hygroscopic
cations migrate to the negative electrode
cathode
anions migrate to the positive electrode
anode
The movement of ions constitutes an
electric current
Substances that conduct an electric current when dissolved in water or when in the molten state are called
electrolytes
Substances that do not conduct electricity are called
nonelectrolytes
electric conductance depends on the concentration of ions
The higher the ion concentration, the greater the electric conductance of the solution.
Compounds that dissociate completely are called
strong electrolytes
Compounds that dissociate into ions only partially are called
weak electrolytes
are important components of the body because they help to maintain the acid–base balance and the water balance
electrolytes
The maximum diameter of the solute particles in a true solution is about
1 nm
If the diameter of the solute particles exceeds this size, then we no longer have a true solution
Colloid
In a colloid (also called a colloidal dispersion or colloidal system), the diameter of the solute particles ranges from about
1 to 1000 nm
two basic characteristics of colloidal systems
- They scatter light and therefore appear turbid, cloudy, or milky
- Although colloidal particles are large, they form stable dispersions
is due to light scattering of colloidal particles
Tyndall effect
When the size of colloidal particles is larger than about 1000 nm, however, the system is unstable and separates into phases.
Suspensions
The motion of the dust particles dispersed in air is a random, chaotic motion. This motion of any colloidal particle suspended in a solvent is called
Brownian motion
why do colloidal particles remain in solution despite all the collisions due to their Brownian motion?
- Most colloidal particles carry a large solvation layer.
- The large surface area of colloidal particles acquires charges from the solution.
is any property of a solution that depends only on the number of solute particles dissolved in the solvent and not on the nature of the solute particles
Colligative property
A system, such as fat in milk, consisting of a liquid with or without an emulsifying agent in an immiscible liquid, usually as droplets of larger than colloidal size
Emulsion
The decrease in the freezing point of a liquid caused by adding a solute
Freezing point depression
is a thin slice of some material, such as cellophane, that contains very tiny holes (far too small for us to see) that are big enough to let small solvent molecules pass through but not big enough to let large solute molecules pass.
Semipermeable membrane
This passage of solvent molecules from the right (solvent or dilute solution) to the left (a more concentrated solution) across a semipermeable membrane is called
Osmosis
The amount of external pressure required to equalize the levels is called the
osmotic pressure
molarity (M) multiplied by the number of particles (i) produced by each formula unit of solute
osmolarity
Two solutions with the same osmolarity are called
Isotonic
The membrane cannot resist the osmotic pressure, and the red blood cells eventually burst, spilling their contents into the water. We call this process
Hemolysis
Solutions in which the osmolarity (and hence osmotic pressure) is lower than that of suspended cells are called
hypotonic solutions
has a greater osmolarity (and greater osmotic pressure) than the red blood cells
hypertonic solutions
If red blood cells are placed in a hypertonic solution water flows from the cells into the glucose solution through the semipermeable cell membrane. This process, called
Crenation
the openings in the membrane are somewhat larger, then small solute molecules can also get through, but large solute molecules, such as macromolecular and colloidal particles, cannot. This process is called
dialysis
contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature
saturated solution
contains less solute than it has the capacity to dissolve
unsaturated solution
contains more solute than is present in a saturated solution
supersaturated solution
the process in which dissolved solute comes out of solution and forms crystals
crystallization
The ease with which a solute particle replaces a solvent molecule depends on the relative strengths of three types of interactions
- Solvent-solvent
- Solvent-solute
- Solute-solute
is a measure of how much solute will dissolve in a solvent at a specific temperature
Solubility
they are completely soluble in each other in all proportions
miscible
the process in which an ion or a molecule is surrounded by solvent molecules arranged in a specific manner
Solvation
the ratio of the mass of a solute to the mass of the solution
percent by mass/ weight/weight
the number of moles of solute dissolved in 1 kg (1000 g) of solvent
molality
Temperature affects the solubility of most substances
true
the separation of a mixture of substances into pure components on the basis of their differing solubilities
fractional crystallization
properties that depend only on the number of solute particles in solution and not on the nature of the solute particles
colligative properties
does not have a measurable vapor pressure
nonvolatile
the partial pressure of a solvent over a solution, P1, is given by the vapor pressure of the pure solvent, P° 1, times the mole fraction of the solvent in the solution
Raoult’s Law
have measurable vapor pressure
volatile
any solution that obeys Raoult’s law
Ideal solution
a procedure for separating liquid components of a solution based on their different boiling points
fractional distillation
the boiling point of the solution (Tb) minus the boiling point of the pure solvent
boiling point elevation
the freezing point of the pure solvent minus the freezing point of the solution
freezing point of depression
the selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one
osmosis
allows the passage of solvent molecules but blocks the passage of solute molecules
semipermeable membrane
the pressure required to stop osmosis
osmotic pressure
made up of one or more cations and one or more anions held together by electrostatic forces
ion pair
a dispersion of particles of one substance (the dispersed phase) throughout a dispersing medium made of another substance
colloid
colloids that are water-loving
hydrophilic
colloids that are water-fearing
hydrophobic