Chemistry Lab C

huppada
Member
Member
Posts: 47
Joined: October 27th, 2016, 6:05 pm
Division: C
State: FL
Has thanked: 2 times
Been thanked: 0

Re: Chemistry Lab C

Post by huppada » February 25th, 2018, 1:27 pm

Nerd_Bunny wrote:
kenniky wrote:
huppada wrote:Chem Lab is allowed to have 5 pages for cheat sheets, but I have no idea how to fill up all the space.
Did anyone completely fill theirs, or does anyone have any ideas for what to add?
Lists of enthalpies, entropies, Gibbs energies, colors

Common constants (ex: anything to do with water)

If you can fit it onto 2 sheets you can make a copy for you and your partner.

I do agree that 5 is overkill for Chem Lab
My partner and I are completely taking advantage of those 5 sheets. Anything we come across, we put on the sheet. We have pretty large font yet still have tons of room.We're also both doing A&P, so we know how much extra sheets can help. I'd recommend adding as many images, charts, and flowcharts as possible. We have an electron configuration chart, (two actually) a phase diagram, an electronegativity chart, and room for a full periodic table. Don't forget to put some common densities and specific heat values on there too. Event supervisors are supposed to give you these values but sometimes they don't. Really take advantage of those 5 pages.
I am also in A&P, and I agree, extra pages really help. But does it get difficult to locate things at times? 5 sheets is really 10 pages, and it seems like a hassle to have to search through those pages in the middle of a competition.
Orlando Science Schools '20
2020 Events: Disease Detectives, Forensics, Protein Modeling

User avatar
Nerd_Bunny
Member
Member
Posts: 137
Joined: January 12th, 2017, 9:36 am
Division: C
State: ID
Location: Gravity Falls
Has thanked: 0
Been thanked: 1 time

Re: Chemistry Lab C

Post by Nerd_Bunny » February 25th, 2018, 1:34 pm

huppada wrote:
Nerd_Bunny wrote:
kenniky wrote: Lists of enthalpies, entropies, Gibbs energies, colors

Common constants (ex: anything to do with water)

If you can fit it onto 2 sheets you can make a copy for you and your partner.

I do agree that 5 is overkill for Chem Lab
My partner and I are completely taking advantage of those 5 sheets. Anything we come across, we put on the sheet. We have pretty large font yet still have tons of room.We're also both doing A&P, so we know how much extra sheets can help. I'd recommend adding as many images, charts, and flowcharts as possible. We have an electron configuration chart, (two actually) a phase diagram, an electronegativity chart, and room for a full periodic table. Don't forget to put some common densities and specific heat values on there too. Event supervisors are supposed to give you these values but sometimes they don't. Really take advantage of those 5 pages.
I am also in A&P, and I agree, extra pages really help. But does it get difficult to locate things at times? 5 sheets is really 10 pages, and it seems like a hassle to have to search through those pages in the middle of a competition.
It hardly takes my partner and I much time to find what we need. All of our vocab is alphabetical, and that takes up about 3 pages. The rest are large images, so usually it takes less than 20 seconds to find something.
Events: A&P, DD, Circuit Lab
States/Nats
2017 DD: 1/16
2018 A&P: 1/29
2019 A&P: 1/22
2019 PM: 1/22 
If you're curious...yes, I like rabbits.

geniusjohn5
Member
Member
Posts: 110
Joined: January 18th, 2017, 6:57 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Chemistry Lab C

Post by geniusjohn5 » March 1st, 2018, 12:48 pm

Can anyone suggest what I should put on my cheat sheet for PHYSICAL PROPERTIES?
The biologist speculates, "What's the meaning of life?"
The physicist asks, "In the universe, does matter really matter?"
The chemist replies, "I shall find solutions to both questions."

User avatar
Nerd_Bunny
Member
Member
Posts: 137
Joined: January 12th, 2017, 9:36 am
Division: C
State: ID
Location: Gravity Falls
Has thanked: 0
Been thanked: 1 time

Re: Chemistry Lab C

Post by Nerd_Bunny » March 21st, 2018, 9:43 am

Has anyone taken the University of Michigan invite test? My partner and I did the test yesterday and we were wondering if anyone was able to correctly do the math on the lab. Advice as well would be really helpful. Thanks!
Events: A&P, DD, Circuit Lab
States/Nats
2017 DD: 1/16
2018 A&P: 1/29
2019 A&P: 1/22
2019 PM: 1/22 
If you're curious...yes, I like rabbits.

kenniky
Member
Member
Posts: 283
Joined: January 21st, 2016, 6:16 pm
Division: Grad
State: MA
Location: ABRHS --> UMichigan
Has thanked: 0
Been thanked: 0

Re: Chemistry Lab C

Post by kenniky » March 21st, 2018, 1:45 pm

Nerd_Bunny wrote:Has anyone taken the University of Michigan invite test? My partner and I did the test yesterday and we were wondering if anyone was able to correctly do the math on the lab. Advice as well would be really helpful. Thanks!
Test writer here-

So let's say you have moles of NaCl and moles of CaCl2; we want to find and .

From the experiment you should get the mass of the sample, the mass of water used , the boiling temperature without dissolved salt , and the boiling temperature with salt .

The boiling point elevation formula says that where is the molality and is the Van't Hoff factor (sp?), which can be approximated as the number of ions that one molecule of a substance dissociates into. In particular, and .

Here, . Since the two salts have different Van't Hoff factors, their contributions need to be calculated separately; , and . Since we assumed moles of NaCl and moles of CaCl2, and . So you end up with , which looks kind of ugly but is just an equation in and since everything else is known.

Also, from the masses you get , note that the s here are mass not molality (why does chemistry use the same symbols for everything qq). So which is also an equation in and .

So you just have a system of equations:

which should be solvable, making sure to account for SI units and such.

For example, if C, C, kg, and g, you have

from which you get moles and moles and then you can find the percent mass from there

In retrospect I probably should have given a procedure for everyone to follow at least, so that they could get to the math here because very few people ended up even considering , or just made it a test question and had a slightly easier lab ... oops

Feel free to ask me other questions about my test if my messy typed out equations didn't make sense lol
Automated Event Assigner!
UMich 2018: Chem Lab, Fermi

[url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
[url]https://scioly.org/wiki/index.php/User:Kenniky[/url]

[url=https://scioly.org/forums/viewtopic.php?t=10008&start=34]2017 Nats = rip[/url]
[url=https://youtu.be/MCo8IAovjfw]ABRHS 2016[/url]

User avatar
Nerd_Bunny
Member
Member
Posts: 137
Joined: January 12th, 2017, 9:36 am
Division: C
State: ID
Location: Gravity Falls
Has thanked: 0
Been thanked: 1 time

Re: Chemistry Lab C

Post by Nerd_Bunny » March 21st, 2018, 2:22 pm

kenniky wrote:
Nerd_Bunny wrote:Has anyone taken the University of Michigan invite test? My partner and I did the test yesterday and we were wondering if anyone was able to correctly do the math on the lab. Advice as well would be really helpful. Thanks!
Test writer here-

So let's say you have moles of NaCl and moles of CaCl2; we want to find and .

From the experiment you should get the mass of the sample, the mass of water used , the boiling temperature without dissolved salt , and the boiling temperature with salt .

The boiling point elevation formula says that where is the molality and is the Van't Hoff factor (sp?), which can be approximated as the number of ions that one molecule of a substance dissociates into. In particular, and .

Here, . Since the two salts have different Van't Hoff factors, their contributions need to be calculated separately; , and . Since we assumed moles of NaCl and moles of CaCl2, and . So you end up with , which looks kind of ugly but is just an equation in and since everything else is known.

Also, from the masses you get , note that the s here are mass not molality (why does chemistry use the same symbols for everything qq). So which is also an equation in and .

So you just have a system of equations:

which should be solvable, making sure to account for SI units and such.

For example, if C, C, kg, and g, you have

from which you get moles and moles and then you can find the percent mass from there

In retrospect I probably should have given a procedure for everyone to follow at least, so that they could get to the math here because very few people ended up even considering , or just made it a test question and had a slightly easier lab ... oops

Feel free to ask me other questions about my test if my messy typed out equations didn't make sense lol
Thank you! This helps so much! My partner will be very pleased to see this. :)
Events: A&P, DD, Circuit Lab
States/Nats
2017 DD: 1/16
2018 A&P: 1/29
2019 A&P: 1/22
2019 PM: 1/22 
If you're curious...yes, I like rabbits.

User avatar
Nerd_Bunny
Member
Member
Posts: 137
Joined: January 12th, 2017, 9:36 am
Division: C
State: ID
Location: Gravity Falls
Has thanked: 0
Been thanked: 1 time

Re: Chemistry Lab C

Post by Nerd_Bunny » March 29th, 2018, 3:20 pm

Would the electromagnetic spectrum come up on a test? I don't think it would, but has anyone had a test question on it?
Events: A&P, DD, Circuit Lab
States/Nats
2017 DD: 1/16
2018 A&P: 1/29
2019 A&P: 1/22
2019 PM: 1/22 
If you're curious...yes, I like rabbits.

User avatar
raxu
Exalted Member
Exalted Member
Posts: 41
Joined: October 9th, 2014, 6:54 pm
Division: C
State: NY
Has thanked: 0
Been thanked: 0

Re: Chemistry Lab C

Post by raxu » April 14th, 2018, 9:51 am

Hi! I was practicing Chem Lab and for a few calculations I didn't agree with the answer key. Can you check my work? Thanks!

1. An object with mass 46.2g displaces 0.34 Liters of water when submerged in a tank. What is the object’s density?
46.2g/340cm^3=0.135g/cm^3.

2. Lead has a melting point of 327.5 °C, specific heat 0.128 J/g ⋅°C, and molar enthalpy of fusion 4.80 kJ/mol. How much heat, in kJ, will be required to heat a 500.0 g sample of lead from 23.0 °C to its melting point and then melt it?
500g*0.128J/gC*304.5C+500g/(207.2g/mol)*4800J/mol=31kJ.

Thanks again!
Richard
Events done Div. B: Simple Machines <3, Shock Value.
Events done Div. C: Astronomy <3 , It's About Time, Forensics, Optics, Remote Sensing, Game On, Materials Science, Mousetrap Vehicle, Fermi Questions, Thermodynamics.

Excelsior
Member
Member
Posts: 2
Joined: May 9th, 2018, 7:45 pm
Division: C
State: TX
Has thanked: 0
Been thanked: 0

Re: Chemistry Lab C

Post by Excelsior » May 9th, 2018, 8:26 pm

If tryouts go well, I will be entering Division C to compete for the next school year. I currently do Potions and Poisons in Division B and I was wondering, are there any concepts that transfer over? I know the topics rotate for Chem Lab but for Potions, everything is just set in whatever the rules are, the only differences being the toxic plants/animals tested. What are the similarities in the two events, if any?

Thanks!
Div B
2016-2017 - Crime, Disease, Fast Facts, Mission Possible
2017-2018 - Crime, Potions, Thermo, Disease, Microbe
Div C
2018-2019 - Forensics, Anatomy, Disease, ExD
2019-2020 - Forensics, Anatomy, Disease, ExD

Seven Lakes Junior High '18, Seven Lakes High School '22

UTF-8 U+6211 U+662F
Exalted Member
Exalted Member
Posts: 1587
Joined: January 18th, 2015, 7:42 am
Division: C
State: PA
Has thanked: 3 times
Been thanked: 7 times

Re: Chemistry Lab C

Post by UTF-8 U+6211 U+662F » May 11th, 2018, 6:14 pm

raxu wrote:Hi! I was practicing Chem Lab and for a few calculations I didn't agree with the answer key. Can you check my work? Thanks!

1. An object with mass 46.2g displaces 0.34 Liters of water when submerged in a tank. What is the object’s density?
46.2g/340cm^3=0.135g/cm^3.

2. Lead has a melting point of 327.5 °C, specific heat 0.128 J/g ⋅°C, and molar enthalpy of fusion 4.80 kJ/mol. How much heat, in kJ, will be required to heat a 500.0 g sample of lead from 23.0 °C to its melting point and then melt it?
500g*0.128J/gC*304.5C+500g/(207.2g/mol)*4800J/mol=31kJ.

Thanks again!
Both look good to me! (Although the density for 1 rounds to 0.136 g/cm^3)

Locked

Return to “2018 Lab Events”

Who is online

Users browsing this forum: No registered users and 1 guest