HiWei

I got methanoic was higher (by like a factor of 10) because it had a higher Ka.

greygoo

the second one was stronger. since this one depended on your answer to the previous part, i'm pretty sure you should still get partial credit if your answer is consistent with your previous results.

also, sig figs really don't matter as long as you're close

squarehead

the first acid. cant remember ne names
Wat was the conc of H+ after the common ion effect
did ne of u guys get like 6.15E-4

biomaster

i said the first acid

primitivefuture

metanoic acid is the first acid.

tbry23m

I said the first acid as well, I think it was 1 x 10-3 and the 2nd one was somewhere around 1 x 10 -4

rifles4watie

"I know everyone is right except the aluminum one (complex ion), although im pretty sure its right."

I think your answer on that is incorrect... the ligand on complex ions must be a multiple of the charge of the metallic ion (3+ for Al)... therefore wouldn't the ligand have a subscript of 3, 6, 9, etc.. ?

(I didn't pick that one to do, though)

maccasweetie

I said the second acid was stronger.... Prop I guess? I don't remember the order. I based it on the Ka values, but I could've been wrong on the second acid's Ka value. I thought it was higher... *shrug*

I said hydrogen pops, but my friend put that the flame would go out. Hmm...

Hecatonchires

Methanoic acid, the second acid, is stronger than propanoic acid, which is supported by the Ka values listed here: http://ifs.massey.ac.nz/resources/ch...n/orgacids.htm

ebonytear

I got C3H7O2 as the empirical formula. YES. That is what I got. Wait, no...I got like 7, 6, and 2. Uh...I think I got it wrong. Shyte. I was so sure about that though! I still am. Gah!

Yeah, I hope the N2 this is write...brown gas would be NO2. I also got more flammable with O2. yeah, and if you think about it SiO2 is glass - that does not react with water to make acid. Although I didn't get the network covalent description - arg.

Methanoic is stronger. That's the one that they give you. The calculuated Ka value was larger...Al should be Al(OH)6^3-. I put Al(H2O)6^3+. LOL.

and for the ionization energy one, it's not because of shielding. it's because you are adding protons but not adding electron shell (so even if you have more electrons, they have negligible mass anyway) so that electrons are same distance from the nucleus but the nucleus is more positive - hence more electrostatic attraction - and bigger pull, equals need more energy to pull off because is closer to nucleus.

Man, this sucks. I was so sure about my empirical formula. For mole ratios, I got like 3.5, 3. and 1. I'm pretty sure my 1 was C. So that would've been like C2H6O7 or something. arg

arg, i'm getting off this thread. it's making me feel less confident in that test, which I thought I totally got a 5 on. Gah!

ebonytear

Oh. This is a better way to do it. What did you guys get for molecular/empirical mass? I got around 122 for both.

KeldoniaSkylar

I got methanoic because it had a higher Ka thus meaning there was more ionization and more H+ ions for a higher pH and a stronger acid. I think I got it to be C7O2H7

ebonytear

yay! I got one of them as 6. But yeah....yay, that has molar mass 123. So i probably had that emp. forumla as well, to get mm= 122...I guess O was my 1. Yeah, methanoic was the one u calculated. that was like 10^-4 while propanoic was 10^-5. higher Ka = more products (numerator) = more ionization. yup yup.

man_on_fire

Here are my errors so far;

1. I got propanoic acid because it had a lower pH and ha higher hydrogen concentration. The rest of 1 I got correct(hopefully). I forgot that pKa matters more than pH.
2. For the rate law one i got M/min when it was 1/min and I put ln(x) instead of ln(H202), which they may give me partial credit on since I just forgot to set x=H2O2.
3. I messed up the products of one of the reactions and got SO2 gas or something.
4. LAB=FAILED!!!! For the splint-test, I just put that Hydrogen will react with the wood, Oxygen will combust with air and nitrogen will decompose. I got CaO basic right but literally bombed everything else.
5. I didn't know formal charge explanation but I got the right structure.

Hopefully that is still a 70-75 percent free-response!!! MC=40-45 maybe?By the way, I am positive you don't need to mention shielding for problem 7. You just use the number of electrons and the depth inside the subshell to answer the ionization energy part. Whatever, we're done so screw this!!!!!!!

KeldoniaSkylar

FR counts for 55% of the test. Which can either be a god send or hurt alot...