For E changing based on molarity,
I remember two different questions Ive done before
Lets say the equation was Cu+2 + Zn(s)–>Cu(s) + Zn +2
One question was like this, if you had two different sets of cells, one set using .50M concentration of both solutions, and the other set using 1.00 M, would the voltage change?
And that answer was no, due to the equation, the part lnQ, since the ration of conc would remain the same .50/.50= 1.0/1.0
@APScholar18: I think thats right.
dude this test is tomorrow and i’m so unprepared lol. its the first year this course has been at our school and test was recently revised in like 2013 and what even am i doing
@shiftydraw and since the new exam doesn’t test us on that equation they most likely won’t ask us that.
I got a 41/50 on the 2014 practice exam? How’s that?
@elyvine - Wait, we don’t have to know the Nernst equation?
@elyvine wait so youre saying dissolving just means it forms bonds with the water?
Thats solid, do decent on the FR and you get a 5
@QasimHassan123: You’re set for a 5 with that score. Can you help me with #29???
@JuicyMango - 29 is pretty much just a Hess’s law question. Multiply the second reaction by 2 and add the two reactions to get the third reaction. Therefore, K3 = K1 + 2K2, which is greater than 1.
@glasshours i don’t think they test on nernst any more but my teacher has said that its good to know it just in case you need to prove something like that example with the two cells
@glasshours yes the curriculum said that the Nernst equation is beyond the scope of the course/ap exam it should be in that huge pdf of learning objectives that college board has for their AP Chem site
@mathman97 substances only dissolve in water because they either exhibit hydrogen bonding or polarity (dipole moments). In the case of water, water doesn’t form bonds like covalent/ionic but it’s polarity causes the molecule to either split apart (like salts) or attach itself well to the water molecule’s opposing dipoles. For example, sugar and ethanol dissolves really easily because those OH groups allow for hydrogen bonding. Oil doesn’t because it is non polar, no hydrogen bonding, and any dispersion forces it has are so weak that it is irrelevant. So when you’re talking about dissolving, you should be thinking about intermolecular forces (h bonding, dipole-dipole, dispersion) at work NOT intramolecular forces like covalent/ionic.
What time are you guys sleeping?
@mathman97 may be helpful to remember like dissolves like. Polars dissolve in polars, and water is polar so only polar substances dissolve in it. There are little exceptions but that’s basically usually true
In an electrolytic cell, does the substance with the less negative reduction potential get oxidized in the anode (since it’s opposite of a galvanic cell)???
Ok, just to see if I understand, if a molecule has some sort of imf bonding with water then it is dissolved?
@apscholar18 gonna try at 10, I’m waking up tomorrow at 6:15 and we are having an ap chem breakfast at 6:45 which should be fun
@APScholar18 - Ideally before midnight, but not sure how I’m going to fall asleep, knowing that I’ve been going to bed at around 2 am for the last two months…
I too have this question.
APScholar18: I want to be able to sleep early so I can be focused during the exam tomorrow, but I’ll realistically be going to bed at 12:00 with the amount of material I still have to review :/.