exam 4

chemical equilibrium

reactants and products occur at a steady state

Chemical equilibrium is

Dynamic

If pure solids or pure liquids are present they have

a value of 1

Equilibrium constant

value describing products and reactants at a given temp

If K > 1

mostly products

If K<1

mostly reactants

Forming products

moving right

forming reactants

moving left

If K > Q

moving right

If K < Q

moving left

If K=Q

Reaction is at equilibrium

Small number approx

initial amount > 2

Le Chatelier’s Principle

equilibrium subjected to change in vol,P,temp, it will shift to get back to equal state

3 types of Stress

addition or subtraction
Change in Vol/Pressure
Change in temp

Addition

moves away from the thing being added

Subtraction

moves towards the subtraction

Increase volume

shifts towards side w more moles of GAS

Decrease vol

shifts towards side w less moles of GAS

Add on inert gas

Ptot increases
no change to equilibrium posiiton

Change in temp

K value changes

endothermic reaction

requires heat

exothermic reaction

produces heat

Weak acids

donate H+ ions

acidc H+

removed in an acid-base reaction
listed BEFORE the carbons in the formula

Nitrogen-based weak acids

have a N with a (+) charge

Weak acid charge

more positive than their conjugate bases

Weak bases

accept H+ ions

No H+ in the formula means

NOT an acid

carboxylates

conjugate base of carboxylic acids

nitrogen-containing weak bases

nitrogen with a neutral charge

Weak base charge

more negative than conjugate acids

Negatively charged acids/bases

Na+, K+, Mg2+

Positive charged acids/bases

NH4Cl

Titrations

lab technique used to determine the amount of one chemical that reacts with another chemical

Bronsted-Lowry acid-base theory

acid donates H
base accepts H

Strong acids/bases

strong electrolytes
Complete dissociation

Weak acids/bases

weak electrolytes
<100 dissociation

HCl

Hydrochloric acid
strong acid

HNO3

Nitric acid, strong acid

HClO4

Perchloric acid, strong acid

H2SO4

Sulfuric acid, strong acid

HBr

Hydrobromic acid, strong acid

HI

Hydroiodic acid, strong acid

NaOH

Sodium hydroxide, strong base

KOH

Potassium hydroxide, strong base

Amphoteric molecules

act as either an acid or a base depending on what they are reacted with

autoprotolysis of water

self, proton, break apart

Kw=

1.0 × 10^-14

If [H+]>[OH-]

Solution is acidic

If [H+]<[OH-]

solution is basic

If [H+]=[OH-]

solution is neutral

pH scale

description of the amount of H+ ion in an aqueous solutions

p-values

take scientific notation and turn it into a more manageable form

pKw=

14.00

pH=

-log[H+]

Acidic solution

<7.00

Neutral solution

7.00

Basic solution

>7.00

[H+]=

2ndlog(-pH)

pOH scale

counter to pH scale

pOH=

-log[OH-]

[OH-]=

2ndlog(-pOH)

Buffer solution

made up of weak acid and conjugate base

Normal pH of blood

7.40

Acidosis

blood gets too acidic

Alkalosis

blood gets too basic

Bicarbonate buffer system

buffer blood with HCO3-

If strong acid is added

new pH goes down

If strong base is added

new pH goes up

Calculate diluted molarities of the weak acid/base using

M1V1=M2V2

solubility equilibrium

type of dynamic equilibrium existing when a solid ionic compound is in equilibrium w a solution of its component ions

classification of solute amounts

unsaturated
saturated
supersaturated

Unsaturated solution

less solute than the solvent can dissolve

Saturated solution

has maximum amount of dissolved solute at a specific temp. No more solute can be added

Supersaturated solution

more solute than predicted

Ksp

equilibrium constant for precipitation/dissolution

sp=

solubility product

Ksp meaning

the larger the value of Ksp, the more soluable
shifts right

Solid value at equilibrium

1

Molar solubility

value of X in an ice chart using Ksp data

Percent ionization =

(g dissolved/g at start) x 100

Common Ion effect

solubility of an ionic compound will decrease when dissolved in solution of its component ions

adding a common ion → adding a product

Products shift left

No ice chart required for what problems

Predicting precipitation reactions

Two ions react. will a precipitate form?

Yes

Dissolution(forming ions)=

shift right

Precipitation(forming solid)

shift left

twice

once

1 Ksp>Q

Dissolution

If Ksp<Q

Precipitation