Road to a 5 in AP Chemistry
The TOP 10 Do’s Per The 2020 Chief Reader,
Paul Bonvallet, Ph.D.
Adapted by L. O’Reilly,Ph.D., member of APTeach.org
#1: Study Past Exams
Learn the format, scope and style
Multiple Choice:
Choose the best answer from the given choices
Claims, Evidence and Reasoning:
A student claims that a mole of carbon and a mole of sodium have the same mass.
Do you agree with the student’s claim? Justify your position.
#1: Study Past Exams
Mathematical Calculations based on data tables
Given the following data, what is the order of the reaction with respect to O2?
Conclusions and predictions based on data tables
Given the following data, predict which substance has the weakest intermolecular forces.
#2: Show Your work, show your work, show your work
SOLUTION CHEMISTRY AND STOICHIOMETRY EXAMPLE:
#3: sHORTCUTS AND MNEMONIC DEVICES HAVE THEIR USES...
TO REMEMBER REDOX: OIL RIG
#3: BUT SHORTCUTS AND MNEMONIC DEVICES HAVE THEIR lIMITS
EXAMPLE M1V1=M2V2
GOOD FOR DILUTIONS
What volume of a 2.50 M Ca(OH)2 solution would be required to reach the equivalence point of a flask that contains 525 mL of a 1.00M HCl solution?
At Equivalence point:
**** # Moles H+ = # Moles OH-
BAD for Titration Calculations
BUT
#4: net ionic equations must show charge and Balance Charge
#5: Reciting a trend is not an explanation
Explain why the size of Na atom is smaller than the size of K atom.
Because the size of an atom increases as you go down a group (TREND!)
Or….
The number of principal energy levels increase by one with every successive new period. Each new principal energy level is further away from the nucleus.
(Electron Configurations Na: [He] 3s1;K: [Ar] 4s1 )
#6: Look for cues for the format and content of your answer
Experimental measurements: Use Significant figures for your final answer
Explain: Remember to get to the real why!
Justify: Mathematical or Words (Scientific Reasoning)
Units: “How many grams” is different than “How many moles”
Agree or Disagree: State which and why
#7: Don’t use mathematical equations blindly
Assign meaning to each variable...
PV = nRT
P= Pressure of (which gas)
V= Volume of container
n= number of moles of (which gas)
R= Universal Gas Constant
T= Temperature in Kelvin (not Time!!)
#8: Intermolecular forces are not bonds
BOND: Force of attraction between 2 atoms within a chemical species
Example:
Covalent
Ionic
Intermolecular force: attraction between two chemical species
Example:
Hydrogen bonding
Dipole-Dipole
London Dispersion
#9: Dimensional Analysis is a helpful error-checking measure
Let the units drive the solution...
#9: Dimensional Analysis is a helpful error-checking measure
And remember that the Universal Gas Constant, R, has two different values/units and applications!
Gas Laws:
Thermodynamics:
#10: Write to be understood
Clarity: Get to the point!
Vocabulary: Use the proper scientific Vocab in the correct context
Order of answers: Answer the first question first-then go onto the second and third!