for 2006, go over gas physical properties i.e. SO2 choking, NO2 brown...etc...
Question 1:
see Nitrogenous Base: NH3, C6H5NH2 etc.
Think Kb ICE Table
Think CONVERT OH- to pOH and THEN to pH = 14 - pOH
Look for addition of salt of conjugate acid! NH4Cl , C6H5NH3Br etc.
use Henderson Hasselbalch to get pH...use DIRECT CONCENTRATIONS given but note that you are NEGLECTING x (ionization) in the equation)
Look for titrating with excess acid....do SRFC to ICE; in ICE table, only use excess STRONG acid as pH determinant.
pKb = pOH at eq. pt BUT PROVE IT.
to get Ka, divide 10-14 by Kb
Question 1:
If you get a SOLID; DO NOT PUT ANYTHING IN THE ICE TABLE FOR IT.
MAKE SURE THAT YOUR CHANGE LINE MATCHES THE COEFFICIENT IN THE BALANCED EQUATION....DRAW AN ARROW!!!!!!!!!!!!!!!!!!
x =1 or 2x = 2 or 3x = 3....etc.
use PV=nRT
and convert n to moles of SOLID to grams of solid.
FOR ANY K expression (easiest points) they will test for coefficients becoming exponents!!
If products and reactants are reversed, K becomes K-1
Question 2:
See Stoichiometry:
ALWAYS PLUG MOLES DIRECTLY INTO THE BALANCED EQUATION
for empirical formulae:
O = 16.0 g/mol of ELEMENTAL ATOMIC OXYGEN
See Freezing Pt. Depression: DON’T forget the I (van t’ Hoff) factor….one for molecules, two or more for salts…..weak acids slightly more than one.
Question 3:
See Kinetics:
COEFFICIENTS TELL YOU RELATIVE RATES OF APPEARANCE AND DISAPPEARANCE!!!
Usually, a products rate of appearance is given RIGHT IN THE DATA.
A + 3C à 2D + 5 F
So, if D is given, Multiply by 1/2 to get A’s rate of disappearance
Multiply by 3/2 to get C’s rate of disappearance.
To get rate law for the second reactant: NEVER PICK TWO EXPERIMENTS THAT HAVE THE SAME CONCENTRATION OF THAT REACTANT because then you will have 1n which is always 1 for ANY n so nothing can be solved.
Rate constant for first order is s-1
Second order is M-1s-1
Etc.
See delta G, H, S
Don’t forget to CHANGE UNITS for S which is usually in J/K
as opposed to delta H or G which are in kJ
to estimate Go with changing T,
use delta G = - RT lnK
or delta G = delta H – T delta S
G is NOT Go
Go IS A CONSTANT for each reactant and determines delta Go for a reaction which determines K which IS A CONSTANT FOR A GIVEN REACTION at a given TEMPERATURE.
WRITE OUT HESS’S LAW GENERALLY FIRST INCLUDING MOLES FROM COEFFICIENTS
So IS NEVER EVEN NEAR ZERO for standard conditions for ANYTHING.
Question 4:
See redox
Acid-base
Combustion
Metal oxide + water = hydroxide + metal ion
Non-metal oxide + water = acid
Transition metal complexes with ammonia, water, Cl-, F-, or SCN-
Solubility rules precipitate: phosphates, carbonates, sulfides
Carbonate or sulfite or sulfide + acid = CO2 or SO2 or H2S
SEE: Lab Question
% error = (experimental – accepted) / ACCEPTED!!!! X 100%
be ready to calculate how an error affects Molar Mass or Molarity
Titrations – last drop from buret should go into ehrlenmeyer flask!!
NEVER DILUTE OR RINSE BURET WITH WATER, IT WILL DILUTE YOUR STANDARDIZED TITRANT
Be ready for titration, molar mass of gas via density ( BEWARE IF COLLECTED OVER WATER!!! EQUALIZE PRESSURE AND THEN SUBTRACT WATER VAPOR PRESSURE AT TEMPERATURE OF WATER BATH = GAS TEMP.)
Question 6:
See bonding:
BONDS ARE NOT ATTRACTIONS!!!
Melting and boiling are generally breaking of ATTRACTIONS (except for metal and network solids)
Hess Cycle for SALTS
For Atomic Structure, s versus d
s electrons are FIRST IN AND FIRST OUT!!!!
Zeff and OCCUPIED PEL’S BOTH must be mentioned to account for trends!!!
H = 1.0079 g/mol of ELEMENTAL ATOMIC HYDROGEN
SUBTRACT H and O mass from CHO compound to get O....do NOT get it from CO2 or from H2O (MOST OF THAT O CAME FROM O2!!!)
