Chemistry Lab C

Jacobi
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Re: Chemistry Lab C

Postby Jacobi » October 21st, 2018, 9:31 am

Dinoswarleafs wrote:Do you think if I got a 5 on AP Chem I'm good for the material I need to know? How do typical test questions and tasks compare to the difficulty of the AP test? Most of it seems pretty basic besides some weird properties we didn't cover like magnetism. I suppose I should memorize the kAs of the acids listed.

It also says that we're only messing with buffers at state level and beyond. Are we just messing with strong acids/bases mostly for the competition?


A 5 on the AP Chem - most people in SciOly get that. Above and beyond is what you need.

Prepare for everything. Weak acids will be covered at all competitions.

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Re: Chemistry Lab C

Postby Dinoswarleafs » October 24th, 2018, 8:18 pm

Jacobi wrote: Weak acids will be covered at all competitions.


Idk why I asked this T_T oops

What are you guys putting on your reference sheet for acids & bases? I put the ions on the rule page and a table of Kas (if weak) and uses of the acids and bases they listed. I was also going to put a list of indicators but it says that the ranges will be provided so that seems pretty useless. I don't really understand what extra stuff there is for titrations if we're not doing buffers until state. Do you guys usually put a ton of stuff on the sheet you get to bring?

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Re: Chemistry Lab C

Postby Jacobi » October 25th, 2018, 6:36 am

Dinoswarleafs wrote:
Jacobi wrote: Weak acids will be covered at all competitions.


Idk why I asked this T_T oops

What are you guys putting on your reference sheet for acids & bases? I put the ions on the rule page and a table of Kas (if weak) and uses of the acids and bases they listed. I was also going to put a list of indicators but it says that the ranges will be provided so that seems pretty useless. I don't really understand what extra stuff there is for titrations if we're not doing buffers until state. Do you guys usually put a ton of stuff on the sheet you get to bring?

I am going to put:
  • Ka table
  • Uses and properties table
  • A few basic equations

Put on everything you know you don't know you know.

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Re: Chemistry Lab C

Postby SochiaK » November 5th, 2018, 7:07 am

Which properties are you guys learning for acids/bases?

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Re: Chemistry Lab C

Postby Jacobi » November 5th, 2018, 7:12 am

SochiaK wrote:Which properties are you guys learning for acids/bases?

I would go to sites like [url]pubchem.ncbi.nlm.nih.gov[/url] and get everything on there. And of course, Wikipedia.

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Re: Chemistry Lab C

Postby meierfra » November 11th, 2018, 1:39 pm

Recommended Lab Equipment for Division C Chemistry Events
Each team may bring any or all of the items listed below for use in Division C Chemistry Events requiring
laboratory equipment. Teams not bringing these items will be at a disadvantage as Event Supervisors will not
provide Recommended Lab Equipment. A penalty of up to 10% may be given if a team brings prohibited lab
equipment to the event.


Does the part about "may bring...all the items listed below" mean that I can use one kit that contains both Chem Lab and Forensics supplies or "penalty...if a team brings prohibited lab equipment" mean that I need a separate kit for each?

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Re: Chemistry Lab C

Postby Jacobi » November 12th, 2018, 4:21 pm

meierfra wrote:
Recommended Lab Equipment for Division C Chemistry Events
Each team may bring any or all of the items listed below for use in Division C Chemistry Events requiring
laboratory equipment. Teams not bringing these items will be at a disadvantage as Event Supervisors will not
provide Recommended Lab Equipment. A penalty of up to 10% may be given if a team brings prohibited lab
equipment to the event.


Does the part about "may bring...all the items listed below" mean that I can use one kit that contains both Chem Lab and Forensics supplies or "penalty...if a team brings prohibited lab equipment" mean that I need a separate kit for each?

I'd side on the latter. You can have a base kit, plus additional items that you take in and out for each event.

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Re: Chemistry Lab C

Postby pikachu4919 » November 15th, 2018, 1:09 pm

Jacobi wrote:
meierfra wrote:
Recommended Lab Equipment for Division C Chemistry Events
Each team may bring any or all of the items listed below for use in Division C Chemistry Events requiring
laboratory equipment. Teams not bringing these items will be at a disadvantage as Event Supervisors will not
provide Recommended Lab Equipment. A penalty of up to 10% may be given if a team brings prohibited lab
equipment to the event.


Does the part about "may bring...all the items listed below" mean that I can use one kit that contains both Chem Lab and Forensics supplies or "penalty...if a team brings prohibited lab equipment" mean that I need a separate kit for each?

I'd side on the latter. You can have a base kit, plus additional items that you take in and out for each event.


I would personally interpret "prohibited items" being stuff that's not on that list at all, especially since stuff that can be used in chem lab could technically be used in forensics even if it's not necessarily useful and even though not everything that's used for forensics can be used in chem lab (i.e. there's no point in using microscope slides and coverslips for chem lab, I would be surprised if that was ever a thing).

disclaimer: not an official rule interpretation, only place for those is soinc.org rule clarifications and FAQ's.
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Re: Chemistry Lab C

Postby starstudent » November 30th, 2018, 9:25 pm

Are periodic tables always provided or should we include one in the cheat sheet?

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Re: Chemistry Lab C

Postby PeptoBismol » December 8th, 2018, 8:29 pm

Do any veterans know how lenient on significant figures? I was doing some problems and I found that answers to weak acid / base pH were sometimes different by at most ~.1 depending if you count "-x" as negligible or not even when you can use 5% rule. Would my answer still be correct if it was .1 off?

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Re: Chemistry Lab C

Postby jaah5211 » December 22nd, 2018, 2:03 pm

PeptoBismol wrote:Do any veterans know how lenient on significant figures? I was doing some problems and I found that answers to weak acid / base pH were sometimes different by at most ~.1 depending if you count "-x" as negligible or not even when you can use 5% rule. Would my answer still be correct if it was .1 off?


Usually if you are one sig fig off, they won't penalize you. However, make sure to ask the proctor. I had an experience where the proctor told me to use to two sig figs for all calculations. In conclusion, depends on the test maker/scorer :D
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Re: Chemistry Lab C

Postby jaah5211 » December 22nd, 2018, 2:05 pm

starstudent wrote:Are periodic tables always provided or should we include one in the cheat sheet?

I suggest you include one in the cheat sheet just in case the proctor doesn't provide it. (although they should)
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Re: Chemistry Lab C

Postby primitive_polonium » January 14th, 2019, 6:51 pm

Longtime vet here; did Acids and Bases when it was a topic in 2013/2014. I am 160% sure the Nats exam is going to be very run of the mill and stuff an AP chemistry grad can do no problem provided they're fast enough and familiar with the Chem Lab format. It's the exams along the way that trip you up.

[quote ="Dinoswarleafs"]What are you guys putting on your reference sheet for acids & bases? I put the ions on the rule page and a table of Kas (if weak) and uses of the acids and bases they listed. I was also going to put a list of indicators but it says that the ranges will be provided so that seems pretty useless. I don't really understand what extra stuff there is for titrations if we're not doing buffers until state. Do you guys usually put a ton of stuff on the sheet you get to bring?[/quote]

Depends on the topic, but problem solving and quickness are the most important assets for acids/bases. The Ka table could be useful. Also would recommend the structures of the common acids in the rules (okay, just ascorbic acid). I wouldn't waste time on indicator lists. Also recommend Henderson Hasselbach and sample problems of how buffers work for each step of the titration curve. I guess there is extra room for proctors to fit in general ideas of titration, not just acid and base titrations.

PeptoBismol wrote:Do any veterans know how lenient on significant figures? I was doing some problems and I found that answers to weak acid / base pH were sometimes different by at most ~.1 depending if you count "-x" as negligible or not even when you can use 5% rule. Would my answer still be correct if it was .1 off?


Depends on the proctor, but most proctors didn't care as long as it was reasonable. I usually put 3 for everything and I as fine. I'm not sure what the stance is on 5% rule. I've seen answer keys that gave points for doing it even when it wasn't needed, and ones that didn't care.

Unrelated to the quotes above but I'd also encourage you to check out more difficult acid/base questions such as the "I dissolve AgC2H3O2 in HC2H3O2; what's the pKa?" type. Also, as mentioned above--calculations at each step of the titration curve.
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Re: Chemistry Lab C

Postby primitive_polonium » January 16th, 2019, 10:34 am

Hey everyone,

I've posted the MIT Chemistry Lab exam https://drive.google.com/drive/folders/1QDMmlj7xcTMobU0Y35LqfybKiJHNPHt_.

All comments welcome!

Idk what the raw score policy will be (it's TBD), but for the time being, here's an axisless graph of scores.

https://imgur.com/qWXS4ds (IDK if image feature works since it's not showing up for me.)
Div D! I really like chem, oceanography, and nail polish--not in that order.

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Feel free to PM me about SciOly or college or whatever! I really enjoy making online friends.


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