GChemistry II Exam 2 Review

Equilibrium

a process that reaches steady state

Chemical equilibrium

when a reaction reaches steady state and there are not changes to reactants or products

Dynamic equilibrium

products are still being formed and the products are breaking back down to reactants

Rate of reaction

the rate of the forward reaction and backward reaction are equal

Physical equilibrium

when physical states are at equilibrium

Equilibrium Constant (K)

the equilibrium constant which relates the products to the reactants at a constant temperature

Law of mass action

at equilibrium the reactants and products have a specific ratio at a constant temperature

Unitless ratio

K is a ratio and is therefore unitless

Products favored

If K is much greater than one the products are favored

Reactants favored

If K is much less than one the reactants are favored

Homogeneous equilibria

when all the reactants are in the same phase

Equilibrium in terms of concentration

we can write the equilibrium in terms of the concentration or the pressure (for gas phase reactions)

Relating Kp to Kc

Kp = KcRT^Δn

Heterogeneous equilibrium

when reactants and products are in different phases

Multiple equilibria

during a lot of reactions, we can see multiple equilibria phases

Equilibrium constant specification

you need to specify the direction of the reaction for the equilibrium constant

Kc value

Kc = 0.0680

Reaction quotient (Qc)

Qc = C^cD^d / A^aB^b

Le Châtelier's Principle

if an external stress is applied to a system at equilibrium, the system adjusts in such a way that the stress is partially offset as the system reaches a new equilibrium position

Bronsted acid

proton donor

Bronsted base

proton acceptor

Conjugate acid-base pair

the acid and the anion that results from the lost proton

Ion Product of Water (Kw)

Kw = [H+][OH-]

pH

pH = -log[H+]

pH Meter

Measures effective concentration of hydrogen ions.

pOH Scale

Measures hydroxide ion concentration, analogous to pH.

pOH Formula

𝑝𝑂𝐻= −log[𝑂𝐻−].

Ion Product of Water

𝐾𝑊= 1.0×10⁻¹⁴ at 25°C.

Strong Acids

Completely dissociate in water.

Examples of Strong Acids

Sulfuric, hydrochloric, and nitric acids.

Weak Acids

Partially dissociate, exist at equilibrium.

Examples of Weak Acids

Acetic acid and hydrofluoric acid.

Conjugate Base

Remains after an acid donates a proton.

Hydronium Ion

Strongest acid that can exist in water.

Equilibrium Constant (Ka)

𝐾𝑎= [𝐻⁺][𝐴⁻]/[𝐻𝐴].

Percent Ionization

Ionized acid concentration at equilibrium.

Henderson-Hasselbalch Equation

𝑝𝐻= 𝑝𝐾𝑎 + log([𝐴⁻]/[𝐻𝐴]).

Buffer Solution

Resists pH changes with weak acid/base.

Titration

Quantitative method to determine acid/base concentration.

Strong Acid-Strong Base Titration

Example: NaOH reacts with HCl.

Weak Acid-Strong Base Titration

Example: Acetic acid reacts with NaOH.

Titration Indicators

Weak acids that change color at pH transition.

Solubility Product (Ksp)

Equilibrium constant for saturated solutions.

Molar Solubility

Moles of solute per liter of solution.

Complex Ions

Metal centers bonded to molecules or ions.

Qualitative Analysis

Determination of ions present in solution.

Common Ion Effect

Equilibrium shift due to added common ion.

Diprotic Acids

Acids with more than one ionizable proton.

Lewis Acid

Electron pair acceptor.

Lewis Base

Electron pair donor.