unit 3

Question 1

What are the four main colligative properties?

Answer 1

1. Vapor pressure lowering
2. Freezing point depression
3. Boiling point elevation
4. Osmotic pressure

Question 2

Relationship between adding a non-volatile solute and volume

Answer 2

Adding a non-volatile solute = decrease solvent per unit volume
- fewer solvent molecules will escape
- entropy of solution increases
- reduces the rate of vaporization

Question 3

What is Raoult’s law?

Answer 3

P solution = (P solvent)(x solvent)

Question 4

Van’t Hoff Factor

Answer 4

Ratio of moles of solute particles to moles of ionic formula units dissolved

Question 5

Relationship between added solutes and entropy

Answer 5

Adding solute, increases entropy

Question 6

Relationship between adding a solute and freezing point

Answer 6

Adding a solute decreases the freezing point

Question 7

Equation to quantify how much the freezing point changes

Answer 7

ΔT = Tf(solution) - Tf(solvent)

Question 8

Define boiling point

Answer 8

The temperature when the vapor pressure is the same as the atmospheric pressure

Question 9

Relationship between adding solute and boiling point

Answer 9

Adding solute increases the boiling point

Question 10

Define osmosis

Answer 10

The passage of a solvent through a semi-permeable membrane from the less concentrated to the more concentrated side

Question 11

What happens when osmosis stops?

Answer 11

Equilibrium has been reached

Question 12

Define isotonic solution

Answer 12

Two solutions have the same osmotic pressure

Question 13

Define hypotonic solution

Answer 13

One solution has a lower osmotic pressure

Question 14

Define hypertonic solution

Answer 14

One solution has a higher osmotic pressure

Question 15

When a solution comes in contact with a pure solvent through a semipermeable membrane, this is referred to as

Answer 15

Reverse osmosis

Question 16

Define dynamic equilibrium

Answer 16

Rate of forward reaction = rate of reverse reaction

Question 17

Homogenous equilibrium vs. heterogenous equilibrium

Answer 17

Homogenous = multiple species of same phase
Heterogenous = species of more than one phase

Question 18

What affects equilibrium?

Answer 18

Anything that affects reaction rates will also affect equilibrium

Question 19

Differentiate between Q and K

Answer 19

Q = reaction constant = ratio of products to reactants at any given point in time
K = equilibrium constant = ratio of products to reactants at equilibrium

Question 20

Q > K

Answer 20

Products decrease, reactants increase
The reaction will proceed backwards

Question 21

Q < K

Answer 21

Products increase, reactants decrease
The reaction will proceed forward

Question 22

Q = K

Answer 22

Products and reactants are at equilibrium

Question 23

What is included in the equilibrium constant?

Answer 23

Just gases, pure liquids and solids are not included

Question 24

K > 1

Answer 24

Product-favored

Question 25

K < 1

Answer 25

Reactant-favored

Question 26

When does Q = K?

Answer 26

When the system is at equilibrium

Question 27

Kc vs. Kp

Answer 27

Kc = equilibrium constant in terms of concentrations of the reactants and products involved in a reaction Kp= equilibrium constant among gases in which the concentrations are measured in terms of partial pressures

Question 28

Kp for Aa +Bb --> Cc + Dd

Answer 28

[C]^c [D]^d / [A]^a . [B]^b

Question 29

The constants are _____ when the number of moles on both sides of the equation are equal.

Answer 29

identical

Question 30

What happens to the reaction when you add more reactant?

Answer 30

Increase concentration, shifts right Push it away (moves away from the change)

Question 31

What happens to the reaction when you remove reactant?

Answer 31

Decrease concentration, shifts left Pull it back (moves toward what you removed)

Question 32

What is heat in an exothermic reaction?

Answer 32

product

Question 33

What is heat in an endothermic reaction?

Answer 33

reactant

Question 34

What happens when you add/remove heat in an exothermic reaction?

Answer 34

Exothermic Add heat = shift left Remove heat = shift right

Question 35

What happens when you add/remove heat in an endothermic reaction?

Answer 35

Endothermic Add heat = shift right Remove heat = shift left

Question 36

What happens when you add pressure to the reaction?

Answer 36

Shifts towards less gas molecules

Question 37

What happens when you remove pressure from the reaction?

Answer 37

Shifts towards more gas molecules

Question 38

What happens when a catalyst is present in a reaction?

Answer 38

It doesn't do anything to the balance (faster not farther)

Question 39

What happens when you increase the volume of the reaction?

Answer 39

Shifts towards the side with more gas molecules Increasing volume decreases pressure

Question 40

What happens when you decrease the volume of the reaction?

Answer 40

Shift towards the side with less gas molecules Decreasing volume increases pressure

Question 41

What is the freezing point depression equation?

Answer 41

ΔT = Kfmi K = constant I= number of particles it dissolves into m = molality

Question 42

What is the relationship between freezing point depression and freezing point?

Answer 42

A higher ΔTf results in a lower freezing point

Question 43

What is the vapor pressure of a solution equation?

Answer 43

Psolution​=Xsolvent​×Psolvent

Question 44

What is X in the vapor pressure of a solution equation?

Answer 44

X = moles of solvent / mol solvent + i+ mol solute

Question 45

What does Raoult's law tell us?

Answer 45

The vapor pressure of a solution

Question 46

What does w/w mean?

Answer 46

Weight by weight (mass percent)

Question 47

If you have two substances that are both nonvolatile, nonelectrolytes what does that mean for I?

Answer 47

I = 1

Question 48

If two substances have the same mass used but one has a larger molar mass, what does that tell us about the solute particles?

Answer 48

Greater molar mass = less solute particles

Question 49

Greater solute particles causes _________vapor pressure

Answer 49

lower

Question 50

Greater solute particles causes ________ freezing point

Answer 50

lower

Question 51

Greater solute particles causes _________ boiling point

Answer 51

higher

Question 52

Greater solute particles causes ________ osmotic pressure

Answer 52

higher

Question 53

What is molality?

Answer 53

mol solute / mass solvent (kg)

Question 54

Adding a nonvolatile liquid results in lower ______

Answer 54

vapor pressure, freezing point, melting point

Question 55

Adding a nonvolatile liquid results in higher ______

Answer 55

boiling point, osmotic pressure