@denilm Allotrope - different amounts of the same element in a substance i.e. O2 and O3.
Isotope - different mass of the same element due to differing number of neutrons. i.e. C-12 and C-14. C-12 has 6 protons and 6 neutrons while C-14 has 6 protons and 8 neutrons
can anyone explain gravimetric analysis and a potential question on it?
@denilm To the best of my knowledge, some people who have it got it from their teachers. However, it is a violation of College Confidential’s Terms of Service to ask for it, or to give it out.
They provide you with the equations for ions reducing into their solid form.
You line a train car with the solid form of the metal, so you would flip the equations (sign for E value flips too).
You want the metal that is least likely to oxidize into its cation, and the reaction with the lowest flipped E value is the least likely to occur.
At t=4, [A] is about .06
The change in concentration of [A] is .06 - .10 = -.04
Since the stoich ratio of A to O2 is 1:1, the change in [O2] is also -.04
.20 - .4 = .16
Does anyone know how to do #4?
http://media.collegeboard.com/digitalServices/pdf/ap/11_3461_AP_CF_Chemistry_WEB_110930.pdf
@taw1020 Thank you!!
For #4, the way I thought about it was that the initial concentrations of A, B, and O2 are the same and the coefficients in the given equation are the same, and therefore the rate constants would be the same.
@bloodythunder No, temperature determines average kinetic energy, so all four have the same for that, however, the equation KE=1/2mv^2 relates velocity and mass, lower the mass of the gas, higher the velocity
@thelinah You use it to calculate the pH or pOH of weak acid or weak base if they are in excess in a solution.
Does anyone know what percent would give me a 3? (Our AP Chem teacher has taught us a quarter of the stuff on the exam… -_-)
42%
What do I need for a 5/4
Anyone have tips for last minute studying?? Anyone have a topic thing for me to know? Any tips for FRQs?!?!
4 is 58%
5 is 72%
speaking of FRQ, any predictions?
for FRQ I’m thinking a thermodynamics, electrochem, gas, and acid/base equilib. easily
^
Don’t forget to write units. Use SigFig rules
btw: could someone write the Sigfig rules 
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do you guys think we’ll be asked to balance redox reactions?
@taw1020 “You line a train car with the solid form of the metal, so you would flip the equations (sign for E value flips too).
You want the metal that is least likely to oxidize into its cation, and the reaction with the lowest flipped E value is the least likely to occur.”
Why?
can anyone help me with this?
do we have to know redox balancing??
@APScholar18 A, B, and D all have negative Ered, meaning the flipped reaction is thermodynamically favorable. The flipped reactions all show oxidation, meaning that the metal that lines the railroad car will essentially corrode. You want the metal that will not oxidize. Idk I can’t put it into words, but if you’re a good test taker, you would notice that choice C has the only Ered that is positive, unlike the others