Chapter 15 Cards Flashcards
surface tension
inward force that tends to minimize the surface area of a liquid; causes the surface to behave like a thin skin
aqueous solution
water that contains dissolved substances
Brownian motion
chaotic movement of colloidal particles, caused by collision with particles of the solvent in which they are dispersed
colloid
mixture whose particles are intermediate in size between those of a suspension and a solute solution
electrolyte
compound that conducts an electric current when it is in an aqueous solution or in the molten state; all ionic compounds are electrolytes, but most covalent compounds are not
hydrate
compound that has a specific number of water molecules bound to each formula unit
emulsion
colloidal dispersion of one liquid in another
nonelectrolyte
compound that does not conduct an electric current in aqueous solution or in the molten state
solute
dissolved particles in a solution
solvation
process that occurs when an ionic substance dissolves; in solution, solvent molecules surround positive and negative ions
solvent
dissolving medium in a solution
strong electrolyte
solution in which a large portion of the solute exists as ions
surfactant
substance that interferes with hydrogen bonding between water molecules and thereby reduces surface tension; ex. soaps and detergents
suspension
mixture from which some of the particles settle out slowly upon standing
Tyndall effect
scattering of light by particles in a colloid or suspension, which causes a beam of light to become visible
weak electrolyte
a solution that conducts electricity poorly because only a fraction of the solute exists as ions
What are some factors that determine how fast a substance will dissolve?
Stirring (agitation), temperature, and surface area of dissolving particles
What factor that determines whether a substance will dissolve?
compositions of the solute and solvent
Why does stirring cause a solute to dissolve faster?
Fresh solvent is continually brought into contact with surface of solute
Does agitation affect the amount of solute that will dissolve?
No
How do higher temperatures increase the rate at which a solute dissolves?
At higher temperatures, kinetic energy of solvent molecules is greater, which leads to an increase in the frequency and force of collisions
Why does granulated sugar dissolve faster than a sugar cube?
Smaller particles in granulated sugar expose much greater surface area to the colliding water molecules
Under what condition will the dynamic equilibrium the exists between a saturated solution and the undissolved solute remain constant?
Constant temperature
How is solubility expressed?
Grams of solute per 100 g of solvent
Partially miscible
Describes liquids that are slightly soluble in each other
What factors determine the amount of solute that will dissolve in a given solvent?
Temperature affects solid, liquid, and gaseous solutes. Pressure also affects solubility of gaseous solutes
What is thermal pollution?
When the increase in temperature of a body of water (caused by the dumping of heated water) lowers the concentration of dissolved oxygen in the body of water
What effect does dilution have on the total moles of solute in solution?
Diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in solution does not change
What are two ways to express the percent concentration of a solution?
Percent by volume or by mass
The terms ‘concentrated’ and ‘dilute’ are only _____ descriptions of the amount of a solute in solution.
Qualitative
The terms ‘concentrated’ and ‘dilute’ are only _____ descriptions of the amount of a solute in solution.
Qualitative
Molarity is also known as ______ _______
Molar concentration
boiling-point elevation
the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent
concentrated solution
a solution containing a large amount of solute
concentrated solution
a solution containing a large amount of solute
What are three colligative properties of solutions?
Vapor-pressure lowering, boiling-point elevation, and freezing-point depression
The ________ in a solution’s vapor pressure is proportional to the number of particles the solute makes in solution.
decrease
dilute solution
a solution that contains a small amount of solute
concentration
a measurement of the amount of solute that is dissolved in a given quantity of solvent; usually expressed as mol/ L
concentration
a measurement of the amount of solute that is dissolved in a given quantity of solvent; usually expressed as mol/ L
colligative property
a property of a solution that depends only upon the number of solute particles, and not upon their identities
freezing-point depression
the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent
immiscible
describes liquids that are insoluble in one another; oil and water are immiscible
immiscible
describes liquids that are insoluble in one another; oil and water are immiscible
unsaturated solution
a solution that contains less solute than a saturated solution at a given temperature and pressure
unsaturated solution
a solution that contains less solute than a saturated solution at a given temperature and pressure
saturated solution
a solution containing the maximum amount of solute for a given amount of solvent at a constant temperature and pressure; an equilibrium exists between undissolved solute and ions in solution
molal boiling-point elevation constant Kb
the change in boiling point for a 1-molal solution of a nonvolatile molecular solute
molal boiling-point elevation constant Kb
the change in boiling point for a 1-molal solution of a nonvolatile molecular solute
mole fraction
the ratio of the moles of solute in solution to the total number of moles of both solvent and solute
supersaturated solution
a solution that contains more solute than it can theoretically hold at a given temperature; excess solute precipitates if a seed crystal is added
