AP Chem - Chapter 11 - Solutions

Question 1

What is a solution

Answer 1

a homogenous mixture

Question 2

what is the difference between a solvent and a solute

Answer 2

a solvent does the dissolving, a solute gets dissolved

Question 3

what are the different ways to find concentration

Answer 3

molarity
mass percent
volume percent
mole fraction
molality

Question 4

what is the equation for molarity (M)

Answer 4

moles solute/liters solution

Question 5

what is the equation for mass percent (%m/m)

Answer 5

mass solute/mass solution x 100

Question 6

what is the equation for volume percent (%v/v)

Answer 6

volume solute/volume solution x 100

Question 7

what is the equation for mole fraction (weird x)

Answer 7

moles solute/total moles

Question 8

what is the equation for molality (m)

Answer 8

moles solute/kg solvent

Question 9

what is the difference between molarity and molality

Answer 9

molarity changes slightly with temperature, molality doesn’t

Question 10

what is the general rule of thumb with solubility

Answer 10

like dissolves like

Question 11

how do you determine the polarity of a molecule

Answer 11

structure

electronegativity and bond polarity

Question 12

what are the three steps in solution formation

Answer 12

breaking up the solute
breaking up the solvent (overcoming intermolecular forces)
allowing the solute and solvent to interact and mix

Question 13

is breaking up the solute (step 1) endo or exothermic

Answer 13

endothermic

Question 14

is breaking up the solvent (step 2) endo or exothermic

Answer 14

endothermic

Question 15

is allowing the solute and solvent to interact and mix (step 3) endo or exothermic

Answer 15

exothermic

Question 16

what is the heat of solution

Answer 16

the sum of the heat values for each step

heat of solution = heat step 1 + heat step 2 + heat step 3

Question 17

what are the factors that affect solubility

Answer 17

structure
pressure
temperature

Question 18

how does structure affect solubility

Answer 18

structure determines polarity, which determines solubility

polar will dissolve in polar, nonpolar in nonpolar

Question 19

how does pressure affect solubility

Answer 19

pressure significantly increases the solubility of a gas

Question 20

what is henry’s law

Answer 20

the amount of gas dissolved in a solution is directly proportional to the pressure of the gas above the solution

Question 21

when does Henry’s law hold true

Answer 21

only when there is no chemical reaction between the solute and the solvent

Question 22

how does temperature affect solubility

Answer 22

most solids dissolve better in warm liquids

gasses dissolve better in cold liquids

Question 23

what is thermal pollution

Answer 23

when factories use water and then put it back put its warm so gasses can’t dissolve as well in it so living things in the pond suffocate.

Question 24

when are the magnitude of the molarity and molality almost the same

Answer 24

in very dilute aqueous solutions

Question 25

what is a nonvolatile solute

Answer 25

one that has no tendency to escape from solution into the vapor phase

Question 26

how does the presence of a nonvolatile solute affect the vapor pressure of a solvent

Answer 26

it lowers it

Question 27

why will a nonvolatile solute lower the vapor pressure of a solvent

Answer 27

because the solvent is occupied with interacting with the solute, so less is available to evaporate

Question 28

what does the lowering of vapor pressure depend on

Answer 28

the number of solute particles present in the solution

Question 29

what is an ideal solution

Answer 29

a liquid to liquid solution that obeys Raoult's Law

Question 30

in solutions where both solute and solvent are volatile, describe the vapor pressure if the solvent/solute have weak interactions (dissimilar IMFs)

Answer 30

vapor pressure will be higher than expected

Question 31

in solutions where both solute and solvent are volatile, describe the vapor pressure if the solvent/solute have strong interactions (similar, very strong IMFs)

Answer 31

Vapor pressure will be lower than expected

Question 32

what can we assume about the IMFs between the solute and the solvent when the energy of formation of solution is large and negative

Answer 32

the IMFs are strong | there will be a negative deviation from Raoult's law

Question 33

what can we assume about the IMFs between the solute and the solvent when the energy of formation of solution is positive

Answer 33

IMFs are weaker than those among the molecules in the pure liquids there will be a positive deviation from Raoult's Law

Question 34

what are colligative properties

Answer 34

properties of a solution that depend only on the number, and not on the identity, of the solute particles

Question 35

How does the presence of a nonvolatile solute affect the freezing point of a solution

Answer 35

It depresses it (lowers it

Question 35

When does the normal boiling point of a liquid occur

Answer 35

At the temperature where the vapor pressure of a liquid equals exactly 1 atm

Question 36

How does a nonvolatile solute affect the boiling point of the solvent

Answer 36

It elevates it

Question 37

Why does the presence of a nonvolatile solute elevate the boiling point of the solvent

Answer 37

Because VP is lowered when we add a solute, so we need to add more energy (higher temperature) to get more solvent to evaporate so the VP will be equal to the atmospheric pressure and be able to boil

Question 38

Why does the presence of a non volatile solute lower the freezing point of the solvent

Answer 38

Solvent is busy interacting with the solute, so we have to remove even more energy to get the solvent to go from a liquid to a solid

Question 39

Why is putting salt on the roads not always effective in keeping them from freezing

Answer 39

Because if the outside temperature is lower than the freezing point of the resulting salt solution, ice forms anyway

Question 40

What is osmosis

Answer 40

The flow of solvent into the solution through the semipermeable membrane

Question 41

What is osmotic pressure

Answer 41

The pressure that must be applied to a solution to stop osmosis

Question 42

How does water tend to move/diffuse

Answer 42

From areas of high concentration to low concentration

Question 43

Why is osmotic pressure particularly useful?

Answer 43

Because a small concentration of solute produces a relatively large osmotic pressure

Question 44

What are isotonic solutions

Answer 44

Solutions that have identical osmotic pressures

Question 45

When does reverse osmosis occur

Answer 45

If a solution in contact with pure solvent across a semipermeable membrane is subjected to an external pressure larger than its osmotic pressure

Question 46

What does reverse osmosis cause

Answer 46

A net flow of solvent from the solution to the solvent

Question 47

What does the semipermeable membrane act as in reverse osmosis

Answer 47

A "molecular filter" to remove solute particles

Question 48

What does the van't Hoff factor (little i thing) account for

Answer 48

The fact that ionic compounds ionize and produce more particles in solution

Question 49

How can you find the expected value for i

Answer 49

By noting the number or ions per formula unit (i.e. NaCl would be 2, K2SO4 would be 3, etc)

Question 50

Is the expected value of the van't Hoff factor always what actually happens?

Answer 50

No

Question 51

Why is the expected value for the van't Hoff factor not always true

Answer 51

Ion pairing

Question 52

What is ion pairing

Answer 52

When dissolved ions in a solution find each other swimming around and hang out for a bit and thus count as a single particle

Question 53

Why do higher concentrations of solute lead to a lower value of the van't Hoff factor

Answer 53

There's more of a chance for ion pairing because there is a higher concentration of ions

Question 54

A salt solution sits in an open beaker. Assuming constant temperature and pressure, the vapor pressure of the solution...

Answer 54

Decreases over time

Question 55

When is ideal behavior for a solution often observed

Answer 55

When the solute-solute, solvent-solvent, and solute-solvent reactions are very similar

Question 56

2 liquids from a solution and release a quantity of heat. How does the pressure above the solution compare to that predicted by raoult's law?

Answer 56

It will be less

Question 57

Why will a nonpolar solute and a highly polar solvent not produce a solution (mix)

Answer 57

Because a large amount of energy would have to be expended