Test 2 Review!

Chemical Kinetics

100

What is chemical equilibria?

A dynamic process that keeps the concentrations of products and reactants constant over time.

200

If Q<K, are the reactants or products favored?

Products are favored.

300

What is the difference between Q and K?

K is the equilibrium constant. Q is the reaction quotient (not @ equilibrium).

400

What does R.I.C.E. stand for?

Reaction

Initial

Change

Equilibrium

500

How can we relate K_p and K_c?

K_p = K_c(RT)^Δn

R= 0.08206 (L*atm)/(mol*K)

Δn= moles of product - moles of reactant

Acid-Base Equilibria

100

What are pH and pOH? How are they related

pH = -log[H⁺]

pOH = -log[OH^-]

pH + pOH = 14

200

True or false: strong bases dissociate into strong conjugate acids.

False! the conjugate will have the opposite strength (weak -> strong; strong -> weak) of the initial acid/base.

300

What is a buffer?

A solution of weak acid or base that resists pH changes over a certain range.

400

What do K_a and K_b mean?

K_a and K_b are the acid and base dissociation constants, respectively.

500

Is water an acid or a base?

It's both!

Solubility

100

What is solubility? Molar solubility?

The amount of solute that dissolves (g/L). 

The amount of solute that dissolves (mols/L).

200

What is K_w?

K_w is the water dissociation constant. 1x10¹⁴

300

What are two ways you can impact solubility?

Stirring

Temperature

Acidity/Alkalinity 

Common Ions

400

Do strong acids and bases have a high or low K_sp? Why?

Really High K_sp. K_sp=[products] and strong acids/bases dissociate completely aka lots of product.

500

Explain the common ion effect?

The common ion effect is the shift in equilibria due to the addition of a common ion.

Ex. H₂CO₃ <-> H⁺ + HCO₃^- 

Adding NaHCO₃ will shift the reaction left, as "product" concentration has increased.

Chemical Reactions

100

What is the K_a expression when vinegar (CH₃COOH) is dissolved in water?

K_a= [H⁺][CH₃COO^-]/[CH₃COOH]

200

I put iron (III) hydroxide into some water, dissociating into Fe³⁺ and 3OH^-. What is the expression for K_sp in terms of ions and x?

Fe(OH)₃ (s) <-> Fe³⁺ + 3OH^-

K_sp=[Fe³⁺][OH^-]³

K_sp=[x][3x]³

300

As H₂O (g) + CO (g) <-> H₂ (g) + CO₂ (g), if more H₂O (g) is added, which way will the reaction shift?

It will shift towards the products.

400

What is the Henderson-Hasselbalch equation? Apply it to acetic acid (HCOOCH₃ <-> H⁺ + COOCH₃^-; pK_a=4.75)

pH = pK_a + log([A^-]/[HA])

pH = 4.75 + log([COOCH₃^-]/[HCOOCH₃])

500

Write the K_w expression for the dissociation of water.

2H₂O (l) <-> H₃O⁺ (aq) + OH^- (aq)

K_w=[H₃O⁺][OH^-]

Misc.

100

Give 2 examples of strong acids and their weak conjugate bases.

HCl -> Cl^-

HBr -> Br^-

H₂SO₄ -> HSO₄^-

HClO₄ -> ClO₄^-

HNO₃ -> NO₃^-

200

What phases of matter are excluded from K_c, K_p, Q, K_a, K_b, and K_sp calculations?

Solids and Liquids

300

Define Le Châtelier's principle.

A system at equilibrium will shift itself in order to maintain equilibrium when acted upon by external stress.

400

What are the two methods we learned for chemical kinetics and R.I.C.E. tables? Explain one of them.

Small-X Approximation = if [reactants]_o and K have a 1000x difference or higher, ignore x in the denominator.

Perfect Squares = if both the numerator and denominator of a K expression are perfect squares, take the square root and avoid the quadratic formula.

 

500

What are the different types of acids and bases? What do they mean?

Arrhenius acid/base - Makes H⁺/ OH^-

Bronsted-Lowry acid/base -> proton donor/acceptor

Lewis acid/base -> Electron pair acceptor/donor