Prepared by: Your Irresponsible Batchmate, Justin Philip B.
Gonzaga
Credits to Joelle Noriko G. Galang for the notes :3
Chemistry 26: Analytical Chemistry
Long Exam 1
Equation Bank + Guide
Solution Process
= + +
: < 0
Spontaneity and Disorder
=
where G is the Gibbs free energy, H is
enthalpy and S is spontaneity (which is always
positive)
Concentration Expressions
Percentage Expressions
1.) Percentage by weight, % (w/w)
100 %
2.) Percentage by volume, % (v/v)
100 %
3.) Mass per volume, % (w/v)
(, , )
100 %
(, , )
Other Expressions
4.) Molarity, M
()
()
5.) Normality, N
=
()
=
Where M is molarity and n is equivalents
()
=
. ()
6.) Equivalent Weight, solute
Where n is a value based on calculations specific
to each distinct type of chemical reaction
* Neutralization Reactions
acid: no. of replaceable (acidic) H+
base: no. of H+ required to neutralize
each mole of base
* Redox Reactions
no. of electrons transferred in the reaction
* Precipitation Reactions
cation: ionic charge
anion: coefficient of cation * charge of
cation)/coefficient of anion
Chemical Kinetics
Rate of Reaction
Given the equation:
+ +
=
[]
[]
[]
[]
=
=
=
Rate Law Expressions
= [1 ] [2 ]
Where m and n are reaction orders of reactant 1
and 2 respectively, m + n is the overall reaction
order, and k is the rate constant
Determining Rate Order
Step 1: Find two sets of data where one
concentration stays constant so it cancels out
Step 2: Apply the following equation
[]1 1
(
) =
[]2
2
1
log ( )
2
=
[]1
log (
)
[]2
Step 3: Find x. Duh
* Linear regression can also be done through
ln = ln[] +
Where m is the reaction order in terms of the
chosen reactant
Order
Integrated Rate Law
Half-life (s)
Rate
Law
k
[] = + []
k[A]
ln[] = + ln[]
k[A]2
1
1
= +
[]
[]
[]
2
ln 2 = 0.612
1
[]
Where the units of k is M/S, 1/S, 1/MS for
reaction orders 1, 2, and 3 respectively
Disclaimer: I may have some mistakes. Please ask around if you feel like theres something wrong with what I have
typed. Its frigging 3:44 AM
Prepared by: Your Irresponsible Batchmate, Justin Philip B. Gonzaga
Credits to Joelle Noriko G. Galang for the notes :3
Problem Solving Tips
Step 1: Identify the substances rate order in the
reaction
Step 2: Solve for the k of the reaction if not given.
This is done through linear regression (x vs y)
on your scientific calculator. Be familiar with your
scientific calculator before the exam.
* Remember to apply ln for 1st orders and
reciprocals for 2nd orders when data plotting
Step 3: Use the equation specified in the table
above
Integrated Rate Law
When to use:
* Given: all the variables except for the one being
solved for (initial concentration, rate constant,
time, and final concentration)
* If youre lacking more than one variable, you
probably missed something / can use another
equation to find the missing variable (probably
rate constant)
Half-life of Substance
When to use:
* Solve for: It specifically asks for half-life or a
paraphrase of it
* Given: most likely just initial concentration.
Recall: solve for rate constant
Arrhenius Equation
1
: ln =
+ ln
1
1
1
2 : ln =
( )
2
2 1
Where Ea is activation energy, R is the gas
constant, 8.314 J/mol k, T is time, and A is the
Arrhenius constant
When to use (linear):
* Usually this is used to do a linear regression
(1/T vs ln k) to solve for activation energy (by
multiplying the slope with R, 8.314 J / mol k;
Note: Activation energy is always positive)
* Another time you have to use this is when
youre being asked for the Arrhenius constant of
the reaction
* The only other time you have to use this is when
youre given all the variables except for the one
youre solving for
When to use (two-point):
* Use this when youre solving for activation
energy and youre only given two data sets (lets
say, initial and final).
* You can use the other form naman but this
saves a LOT of time
Chemical Equilibrium
Given the equation:
+ +
Equilibrium Constant, kc
[] []
[] []
Note: Kc values are dimensionless because they
involve a thermodynamic quantity called activity, a
ratio of a substances concentration/partial
pressure to a standard. Liquids and solids have
activities approaching 1, making them value-less in
the computation.
The Reaction Quotient, Q
[] []
[] []
Where the concentrations are not necessarily
equilibrium values
Problem Solving Tips:
* When being asked about where the reaction
would proceed based on Q and Kc, compare them
with Kc on the left. Follow the direction of the
comparison sign. (e.g. Kc > Q, the reaction
proceeds to the right)
Solving for Q and Kc/Kp: The ICE Table
Initial
Change
Equilibrium
+ +
A, unit B, unit C, unit D, unit
-ax
-bx
+cx
+dx
-ax - bx + cx + dx
[ + cx] [ + dx]
[ ax] [ bx]
Notes:
* Make sure that the entire table uses only ONE
unit. It can be in molarity (M, mol/L), moles
(mol), or atm (pressure)
Disclaimer: I may have some mistakes. Please ask around if you feel like theres something wrong with what I have
typed. Its frigging 3:44 AM
Prepared by: Your Irresponsible Batchmate, Justin Philip B. Gonzaga
Credits to Joelle Noriko G. Galang for the notes :3
* Notice how the change in amount x is still
affected by the stoichiometric coefficients. Lets
say that youre given an initial of 0 M and a final
of 20 M with a coefficient of 2. The change, x,
isnt actually 20, because 2x = 20, so x is actually
10 M
* Important: Do NOT forget about the powers
in the Kc computation.
* Its a REACTION QUOTIENT, Q, if youre
solving with non-equilibrium concentrations.
Le Chateliers Principle
1. Changes in concentration: proceed toward
direction to lessen stress
2. Changes in volume and pressure
volume or pressure: toward lower
number of molecules
volume or pressure: toward greater
number of molecules
3. Changes in temperature: treat temperature as a
part of the reaction. (endothermic, reactant while
exothermic, product)
Partial Pressures
Recall:
=
=
Equilibrium Constant in terms of Partial Pressures
( ) ( )
=
( ) ( )
Note: Only gaseous reactant/products will be
included in the computation.
Relationship between Kc and Kp
= ()
= ()
Where Kp is the equilibrium constant in terms of
partial pressure, Kc is the equilibrium constant in
terms of concentration, R is the gas constant,
0.08206 L atm/mol, T is the temperature and n
is mol gaseous products mol gaseous reactants.
Problem Solving Tips
* Dont waste time doing a long cut if you can just
relate the Kc and the Kp.
* You usually use this when you want an easy way
of converting between Kc and Kp.
* Dont get confused. Use the respective
equilibrium constant based on the unit you chose
for your ICE table.
* Remember: Kp only involves gaseous
substances.
Relationship between Go and the Equilibrium Constant
Remember: Go is defined as the standard free
energy change at standard conditions (1 M, 1
ATM)
= + ln
Where R is the gas constant, 8.314 J/mol k, T is
the absolute temperature, and Q is the reaction
quotient.
At equilibrium, where Go = 0 and Q = K
= ln
Ionic Equilibria: Acids and Bases
Definitions:
1. Arrhenius:
acid: contains H, produces H+
base: contains OH group, produces OH2. Brnsted-Lowry:
acid: proton donor
base: proton acceptor
3. Lewis:
acid: electron pair acceptor
base: electron pair donor
4. Amphoteric: can behave as an acid or base
5. Amphiprotic: can behave as an acid or a base in
a proton transfer reaction
Relative Strengths (Binary Acids)
* Down a group: in size; in energy to break Hbond (electronegativity) = acidity
* Across a period: in energy to break H-bond
(electronegativity) = acidity
Relative Strengths (Ternary Acids)
* hydroxides of nonmetals the produce H3O+ in
water
* acidity of acids with same central elements
increase with the increase in oxidation state of
central element and increase in oxygen atoms
Autoionization of Water
+
2 () + 2 () 3 ()
+ ()
+
= [3 ][ ] = = 1.0 1014
Note: at 25o C
Disclaimer: I may have some mistakes. Please ask around if you feel like theres something wrong with what I have
typed. Its frigging 3:44 AM
Prepared by: Your Irresponsible Batchmate, Justin Philip B. Gonzaga
Credits to Joelle Noriko G. Galang for the notes :3
Ionization Constants for Weak Monoprotic Acids and
Bases
[ + ][ ]
=
[]
[ ][+ ]
=
[]
Problem Solving Tips:
Step 1: Identify the concentrations at equilibrium
using the ICE table
Step 2: Set-up the equilibrium constant equation
using the equilibrium values with variables
Step 3: If the denominator is (something x), you
can check if you can disregard the x by seeing if
the following is satisfied
/
> 1000
/
Step 4: Solve for x using the quadratic formula or
a solver
Step 5: Eliminate extraneous solution by checking
for negative concentration values through
substitution in the ICE table.
Step 6: Solve for what is being asked
Remember: Dont make any long cuts. Think of
the fastest way you can arrive at the solution
before inputting data to save time.
Conversion Factors
Pressure
1 = 760
= 760 = 101,325
1 ~ 1 (0.9869 )
Temperature
+ 273.15 =
9
+ 32 =
5
Acidity
+ = = 14
Percent Ionization of Weak Acids/Bases
[ ]
% =
100 %
[]
[+ ]
% =
100 %
[]
Dealing with Polyprotic Acids and Bases
* Dont panic. Figure out the starting ions present
in the solution. Make sure that youre using the
right dissociation constants for your calculations.
* You will have to use multiple ICE tables. To
save time, always check if x can be disregarded.
* Make sure that you adjust the concentrations of
hydronium/hydroxide ions after the first ICE
table.
* Make sure you answer the question properly.
Disclaimer: I may have some mistakes. Please ask around if you feel like theres something wrong with what I have
typed. Its frigging 3:44 AM
