Chem 104, General

Question 1

Lewis Base

Answer 1

e- pair donor Draw Lewis diagram and look for lone pairs; a Lewis base must have e- to donate.

Question 2

Lewis Acid

Answer 2

e- pair acceptor + charged substances make great Lewis acids, but others can be too. Draw a Lewis diagram and make sure molecule has a place to attach.

Question 3

HCl

Answer 3

Hydrochloric Acid strong acid

Question 4

HBr

Answer 4

Hydrobromic Acid strong acid

Question 5

HI

Answer 5

Hydroiodic Acid strong acid

Question 6

HNO3

Answer 6

Nitric Acid strong acid

Question 7

HClO4

Answer 7

Perchloric Acid strong acid

Question 8

H2SO4

Answer 8

Sulfuric Acid strong acid

Question 9

LiOH

Answer 9

Lithium Hydroxide strong base

Question 10

NaOH

Answer 10

Sodium Hydroxide strong base

Question 11

KOH

Answer 11

Potassium Hydroxide strong base

Question 12

RbOH

Answer 12

Rubidium Hydroxide strong base

Question 13

Ca(OH)2

Answer 13

Calcium Hydroxide strong base

Question 14

Sr(OH)2

Answer 14

Strontium Hydroxide strong base

Question 15

Ba(OH)2

Answer 15

Barium Hydroxide strong base

Question 16

Comparing strength of bionary acids within the same GROUP on the period table…

Answer 16

…within a group, acidity increases as bond strength decreases, so larger molecules are less electronegative and acid is stronger (Proton disassociates more easily). So, acids get strong as you go down a group on the periodic table. (HBr very strong)

Question 17

Comparing strength of bionary acids with the same PERIOD on the periodic table…

Answer 17

…within a period, acidity increases as bond polarity increases, so acid strength increases as you move from left to right across a period on the periodic table. (HBr very strong)

Question 18

Def of Amphiprotic Compond

Answer 18

Can behave as both an acid and a base

Question 19

Ratio of base: acid in a good buffer solution?

Answer 19

Ratio of [b]/[a] must be greater than or equal to 0.10 or less than or equal to 10.0.

Question 20

Henderson Hasselbalch Equation

Answer 20

pH= pKa + log [base]/[acid]. base/acid is a ratio, so can use moles instead of concentration. Used for buffers, plus the midpoint (buffer) phase of titrations.

Question 21

Ksp

Answer 21

Solubility constant. Larger Ksp = more soluable. QKsp, solution is super-saturated and unstable. A precipitate forms as EQM is established.

Question 22

Spontaneous Process (in Thermodynamics)

Answer 22

any physical or chemical process that proceeds to a lower, more thermodynamically stable state. (vs. nonspontaneous)

Question 23

How does thermodynamic stability keep a reaction from occurring?

Answer 23

The reaction does not occur because delta G > 0 (positive).

Question 24

How does kinetic stability keep a reaction from occurring?

Answer 24

The reaction does not occur because the activation energy barrier Ea is too high.

Question 25

Axis on a Van't Hoff plot

Answer 25

lnK vs. 1/T This gives a straight line, which can be used to determine entropy and enthalpy change.

Question 26

What is a spontaneous process?

Answer 26

Any physical or chemical process that proceeds to a lower, more thermodynamically stable state. = Matter has spread out evenly. Looking at microstates, the macrostate with even distribution is always the most probable. (ex. heat flowing into surroundings)

Question 27

Given 10 molecules, 2 chambers, what is the probability of them all being in the left flask?

Answer 27

Each of the 10 molecules has a 1/2 chance of being in the left. =0.5^10

Question 28

How to calculate number of microstates

Answer 28

W = n ^N # of microstates = #chambers ^#molecules (This is where entropy comes in)

Question 29

How to calculate the number of macrostates

Answer 29

1 + # of molecules

Question 30

allotrope

Answer 30

Different states of the same element. ex. Graphite and diamond are allotropes of Carbon.

Question 31

Second Law of Thermodynamics

Answer 31

Considering the system and surroundings, a spontaneous process will occur in the direction that increases the entropy of the universe. Delta S_universe is \>0 for a spontaneous reaction. - (T delta S_universe) = delta G_system

Question 32

Delta G vs. Delta G°

Answer 32

Delta G is a variable. (analagous to reaction quotient Q). Delta G° is a constant. (analagous to equilibrium constant K)

Question 33

When are Delta G and Delta G° equal?

Answer 33

Under standard conditions, when Q=1 and so lnQ=0.

Question 34

What is special when Q = K?

Answer 34

reaction is at equilibrium. Also, delta G = 0 and delta G = delta G°

Question 35

Reaction is product favored when delta G is \_\_\_\_\_, and K is \_\_\_\_\_\_\_\_\_\_.

Answer 35

Reaction is product favored when delta G is negative, and K is positive (products/reactants).

Question 36

What keeps a chemical process from occurring?

Answer 36

1. thermodynamic stability --delta G \>0 2. Kinetic stability --activation energy barrier is too high