Unit 16 - Solutions and Solvents Exam

What is a solution?

Homogeneous mixtures that can be solids, liquids, or gases,

What is a solute?

A substance that is dissolved in a solution.

What is a solvent?

The substance that dissolves the solute

What are the three factors that determine the rate at which a solute dissolves?

Stirring/ agitation, temperature, and the particle size of the solute

What does stirring do to a solution?

It speeds up the rate of dissolving because it disperses the solute and brings the solute in contact with all of the solvent particles

What does increasing the temperature of a solution do?

It increases the rate at which a solid solute dissolves because the particles are moving faster

Where does dissolving occur?

Only at the surface of the particle

How does a smaller particle increase the rate of dissolving?

The smaller the particles, the more surface area the solvent can dissolve in

What is solubility?

The amount of solute that dissolves in a given quantity of solvent at a specific temperature

What are the units for solubility?

grams of solute / 100 grams of solvent

What makes the solubility increase?

The stronger the attractions between the solute and the solvent molecules are, the more it'll increase

What is an unsaturated solution?

A solution that contains less than the maximum amount of solute and a given temperature.

If more solute is added to an unsaturated solution what will happen?

The solute will dissolve

What is a saturated solution?

A solution that contains the maximum amount of solute at a given temperature

If more solute is added to a saturated solution, what will happen?

The solute will settle at the bottom

What is a supersaturated solution?

A solution that contains more than the maximum amount of solute at a given temperature and is extremely unstable

If more solute is added to a supersaturated solution, what will happen?

A fast recrystallization of the previously dissolved solute occurs

What happens to the solubility of a solid when the temperature increases?

The solubility tends to increase

What does not affect the solubility of a solid solute?

A change in pressure

What is a miscible solution?

A solution where two liquids will dissolve into each other

What is a immiscible solution?

A solution where two liquids won't dissolve into each other

What happens to the solubility of a gas when the temperature increases and why?

The solubility tends to decrease because the gas particles need to be as slow as possible to force them into a liquid solvent

What happens to the solubility of a gas when the pressure increases and why?

The solubility tends to increase because the particles are being forced into a liquid

What relationship does Henry's Law show?

It shows the relationship between pressure and the solubility of a gas, including Henry's Law Constant

What is the concentration of a solution?

The measure of the amount of solute that is dissolved in a given amount of solvent

What is a dilute solution?

A solution that contains a small amount of dissolved solute

What is a concentrated solution?

A solution that contains a large amount of dissolved solute

What is molarity and what is the symbol that represents it?

It is the number of moles of solute dissolved in one liter of solution. It's represented by M

What is the formula for molarity?

M = moles of solute / liters of solution

What is the formula for a mole fraction?

Mole fraction = moles of component / total moles

What does the molarity of a solution change?

It changes the temperature because the contraction and expansion of the solution changes the volume

What does diluting a solution do?

It reduces the number of moles of solute per volume, but does not change the total number of moles of solute in solution

What needs to happen in order for a dilution to happen?

More solvent needs to be added to the solution

What is the formula for a dilution?

M1 x V1 = M2 x V2

** The molarity of the more concentrated stock solution (M1) is always larger than the molarity of the dilute solution (M2)**

How can the concentration of a solution also be expressed?

It can also be expressed by percent by volume or the percent by mass of the solute.

What is the percent by volume formula?

(%V/V) = ( volume of solute / volume of solution ) x 100

What is the percent by mass formula?

(%M/M) = ( mass of solute / mass of solution ) x 100

What is a colligative property?

A property that depends only upon the number of solute particles (not the type)

What are the four colligative properties?

vapor pressure depression, boiling point elevation, freezing point depression, and osmosis

What is vapor pressure depression?

The pressure of a vapor above a liquid

What happens to the vapor pressure when solute particles are added?

The vapor pressure decreases because the solvent particles are attracted to the solute particles, so they do not want to leave the solution and become vapor

What happens to the freezing point when solute particles are added?

The freezing point lowers because when a solute is added, the solvent particles are attracted to the solute, so they do not want to get in that arrangement. The temperature must be lowered to force them into a solid arrangement

What happens to the boiling point when solute particles are added?

The boiling point increases because when a solute is added, the solvent particles are attracted to the solute, so they do not want to leave the solution and become a gas. The temperature must be raised to force them to become a gas

What does semipermeable mean?

Materials that only allow some molecules to pass through

What is osmosis?

The net movement of solvent toward the solution with the higher solute concentration

What are the three types of solute particles?

Atoms, ions, or molecules

** Ionic compounds break into multiple ions when dissolved in water **

What is the difference between molarity and molality

Molality is moles of solute per kg of solvent while molarity is moles of solute per liter of solution

What is molality?

m = moles of solute / kg of solvent

What is the freezing point depression formula?

ΔTf = Kf x m

What is the freezing point formula?

FP = (freezing point of substance) - ΔTf

What is the boiling point elevation formula?

ΔTb = Kb x m

What is the boiling point formula?

BP = (boiling point of substance) + ΔTb

What is the effective molality formula?

EM = (number of particles) x m