CHEM 106 Exam 2 Study Guide

Adding reactant to an equilibrium

shifts to the right

removing reactant from an equilibrium

shifts to the left

removing product from an equilibrium

shifts to the right

for an endothermic rxn, increasing temperature to an equilibrium

shifts to the right

for an exothermic rxn, increasing temperature to an equilibrium

shifts to the left

Increasing pressure on an equilibruim rxn

shifts toward the side with fewer moles of gas

Decreasing pressure on an equilibrium rxn

shifts toward the side with more moles of gas

Increasing volume on an equilibrium rxn

shifts toward the side with more moles of gas

Decreasing volume on an equilibrium rxn

shifts toward the side with fewer moles of gas

What if both sides have equal moles of gas?

Volume and Pressure do not affect equilibrium 

What is the Arrhenius definition of Acids and Bases?

Arrhenius Acids: a substance that produces H+ in water

Arrhenius Bases: a substance that produces OH- in water

What is the Bronsted-Lowry Definition of Acids and Bases?

Bronsted-Lowry Acids: acids are proton donors

Bronsted-Lowry Bases: bases are proton acceptors

Acid Base Neutralization:

H+(aq) + OH- (aq) → H2O

Conjugate Acid-Base pairs definition

Two substances that differ only by one exchangable H+

How to make an acid into a conjugate base?

Remove H+

How to make a base into a conjugate acid?

Add H+

What is the difference in acid strength?

a strong acid dissociates completely while a weak acid has an equilibrium

What are the 7 strong acids?

HCl, HBr, HI, H2SO4, HNO3, HClO4, HClO3

(hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, perchloric acid, and chloric acid

Common Weak acids:

acetic acid, R-COOH (carboxyl groups), H3PO4

Water can be a proton donor or proton acceptor

True

What does Kw equal?

1.0 × 10^-14

Another way to calculate Kw

Kw = [H3O+][OH-]

How to find pOH from pH

14-pH=pOH

The stronger the acid, the ______ the Ka value

larger; because the equilibrium lies further to the right

Calculating % ionization

[ ]equilibrium / [ ] initial

What are the 7 strong bases?

Group one: LiOH, NaOH, KOH, RbOH

Group two: Ca(OH)2, St(OH)2, Ba(OH)2

Recognizing weak bases

1. N-centered compounds

2. amines (n-centered compounds + carboxyl groups)

How do you recognize a basic salt solution?

The anion contains the conjugate base of a weak acid

How do you recognize a neutral salt solution?

The anion contains the conjugate base of a strong acid (except HSO4-)

How do you recognize an acidic salt solution?

If the cation is the conjugate acid of a weak base, the salt is acidic

Common basic salts

K3PO4, Na2HPO4

Common neutral salts

NaCl, KNO3, KBr, RbClO4, LiI, LiClO3

As electronegativity decreases, acid strength

increases

As the number of oxygen molecules increase, acid strength

increases

What is a buffer solution?

Buffer solutions are solutions that resist changes in pH - it is composed of a weak acid and its conjugate base

Buffers MUST be a ____ acid

weak

Henderson Hasselbalch Eqn

pH = pKa + log([base]/[acids])

Reactant favored reactions yield a ______ equilibrium than product favored reactions

quicker

K > 10

product-favored

K < 0.1

reactant-favored

0.1 < K < 10

significant amounts of both

Equilibrium occurs when the rate of the forward reaction ____ the rate of the reverse reaction

equals

Reverse reactions of K

results in 1/K

Changing stoichiometric coefficients

raises K^n

Q uses ____ concentrations while K uses _______ concentrations

initial; equilibrium

As acid strength increases; its conjugate base strength _______

decreases