20 terms

Chemistry test: solutions

STUDY
PLAY

Terms in this set (...)

what is the difference between solvent and solute?
solvent does the dissolving, solute is dissolved
what determines whether a solute will be soluble in a given solute?
polarity - like dissolves like

nonpolar: equal (ex. CCL4)
polar: not equal (ex. water)
explain the difference between saturated and unsaturated solutions.
saturated - maximum amount of solute is dissolved
unsaturated - more solute can be dissolved
what are 3 ways to increase the rate of solvation?
stir, increase surface area, increase temperature
why are gases less soluble at higher temperatures?
higher energy causes them (gas) to leave the solution
what is the difference between molarity and molality?
molarity you divide by liters (L) of solution
molality you divide by kilograms (kg) of solvent
how does a solute affect the boiling point of a solution?
increases
describe osmosis
solvent moving from less concentrated solution to a more concentrated solution through a semipermeable membrane
what is a colligative property?
depends on number of particles present but not their identity
what are the two types of heterogeneous properties and how do they differ?
suspension - settle when standing
colloid - do not settle
what is a homogeneous mixture? what are its properties?
solution; small particles, cant be filtered, doesn't scatter light
explain the solvation process.
the solvent particles surround the solute particles and break the solute apart, making it appear as if the solute has disappeared. The negative molecules of the solvent will attracted to the positive molecules of the solute and vise versa.
how does pressure affect the solubility of a gas in a liquid?
what law is a statement of this property?
if the pressure of a gas above a liquid is increased what happens to the amount of the gas that will dissolve in the liquid, if all other conditions remain the same?
- increase in pressure increases solubility
- Henry's law
- the amount of gas that will dissolve increases
why does a bottle or can of soda effervesce when opened?
When the can or bottle is opened, the pressure on the gas is greatly reduced, initiating the process of bubble formation (effervescence). Bubbles of carbon dioxide gas float to the surface and escape the beverage and float into the air.
What is the heat of solution? In what unit is it expressed? What is the significance of the positive and negative signs associated with heats of solutions?
- heat of solution is the energy required to dissolve something
- KJ/mol
- positive means endothermic
-negative means exothermic
Explain why electrolytes can conduct electricity but nonelectrolytes can't. Give an example of each.
Electricity requires charged particles that can move. Electrolytes break into charged particles in the solution and can therefore conduct electricity, while nonelectrolytes do not break a part and cannot conduct electricity.

Ex: salt is an electrolyte; sugar is a nonelectrolyte
given an unknown mixture of two or more substances explain one technique that could be used to determine whether that mixture is a true solution, a colloid, or suspensions.
Filtering or the Tyndall effect

solutions: small particles, do not separate, cannot be filtered, do not scatter light
colloids: medium particles, do not separate, cannot be filtered, scatter light
suspension: large particles, settle out, can be filtered
electrolyte vs. nonelectrolyte
nonelectrolyte: covalent compounds (two nonmetals), do not conduct electricity
electrolyte: ionic compounds (metal & nonmetal, acids, bases, polyatomic ions), do conduct electricity
list some common properties that can dissolve in water.
NaCl --> salt
ethanol
KNO3
Ca(OH)2
list colligative properties
(depends on number of particles, not their identity)
1. boiling point elevation
2. freezing point depression
3. osmotic pressure
4. vapor pressure lowering