Chem Lab C

Test your knowledge of various Science Olympiad events.
kenniky
Member
Member
Posts: 283
Joined: January 21st, 2016, 6:16 pm
Division: Grad
State: MA
Location: ABRHS --> UMichigan

Re: Chem Lab C

Postby kenniky » February 2nd, 2017, 9:11 am

I guess I'll answer that.
Doesn't seem too bad
12.2 °C
correct, you can ask a question now
Automated Event Assigner!
Tests Written
UMich 2018: Chem Lab, Fermi [url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
Results
[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]

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 2nd, 2017, 5:20 pm

Alrighty, here's one.

5 mole samples of CO2, H2O(vapor), Ne, and CH4 are placed in separate, identical 10L cylinders at 25 °C.
a. What pressure, in mm Hg, would be generated? Assume near-ideal behavior.
b. If all of the samples were to be combined into one 20 L container, what pressure would that container be?
c. Holes are punctured in the ends of each of the identical cylinders so as to allow each of the gases to diffuse. From least to greatest, list the relative amount of time that it would take each gas to diffuse.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

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

Re: Chem Lab C

Postby kenniky » February 3rd, 2017, 1:58 pm

Alrighty, here's one.

5 mole samples of CO2, H2O(vapor), Ne, and CH4 are placed in separate, identical 10L cylinders at 25 °C.
a. What pressure, in mm Hg, would be generated? Assume near-ideal behavior.
b. If all of the samples were to be combined into one 20 L container, what pressure would that container be?
c. Holes are punctured in the ends of each of the identical cylinders so as to allow each of the gases to diffuse. From least to greatest, list the relative amount of time that it would take each gas to diffuse.
Answer
a. PV = nRT P * 10L = 5 mol * 0.08206 atm L/mol K * 298 K => P = 12.227 atm = [b]9292 mmHg [/b] b. total: 20 mols do the same thing P =[b] 24.45 atm = 18580 mmHg[/b] c. MM CO2 = 44, MM H2O = 18, MM Ne = 20, MM CH4 = 16 Fastest - CH4 - H2O - Ne - CO2 - Slowest
Automated Event Assigner!
Tests Written
UMich 2018: Chem Lab, Fermi [url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
Results
[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]

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 3rd, 2017, 3:51 pm

Alrighty, here's one.

5 mole samples of CO2, H2O(vapor), Ne, and CH4 are placed in separate, identical 10L cylinders at 25 °C.
a. What pressure, in mm Hg, would be generated? Assume near-ideal behavior.
b. If all of the samples were to be combined into one 20 L container, what pressure would that container be?
c. Holes are punctured in the ends of each of the identical cylinders so as to allow each of the gases to diffuse. From least to greatest, list the relative amount of time that it would take each gas to diffuse.
Answer
a. PV = nRT P * 10L = 5 mol * 0.08206 atm L/mol K * 298 K => P = 12.227 atm = [b]9292 mmHg [/b] b. total: 20 mols do the same thing P =[b] 24.45 atm = 18580 mmHg[/b] c. MM CO2 = 44, MM H2O = 18, MM Ne = 20, MM CH4 = 16 Fastest - CH4 - H2O - Ne - CO2 - Slowest
Yup! Your turn.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

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

Re: Chem Lab C

Postby kenniky » February 3rd, 2017, 8:34 pm

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
Automated Event Assigner!
Tests Written
UMich 2018: Chem Lab, Fermi [url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
Results
[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]

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 8th, 2017, 8:40 am

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
On wow, forgot this could be on here. Glad to see this before anything important.

Fortunately I still think I know the equation
100.7 °C?
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

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

Re: Chem Lab C

Postby kenniky » February 8th, 2017, 4:15 pm

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
On wow, forgot this could be on here. Glad to see this before anything important.

Fortunately I still think I know the equation
100.7 °C?
Incorrect, check your equation again (I'm pretty sure I know where you went wrong)
Automated Event Assigner!
Tests Written
UMich 2018: Chem Lab, Fermi [url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
Results
[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]

Piggy
Member
Member
Posts: 24
Joined: August 4th, 2015, 11:43 am
Division: C
State: NY

Re: Chem Lab C

Postby Piggy » February 9th, 2017, 1:16 pm

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
.
102.1 °C?

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

Re: Chem Lab C

Postby kenniky » February 9th, 2017, 1:30 pm

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
.
102.1 °C?
correct, your turn
Automated Event Assigner!
Tests Written
UMich 2018: Chem Lab, Fermi [url=http://tinyurl.com/kenniky-so-test]Rate my tests![/url]
Results
[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]

Piggy
Member
Member
Posts: 24
Joined: August 4th, 2015, 11:43 am
Division: C
State: NY

Re: Chem Lab C

Postby Piggy » February 9th, 2017, 4:32 pm

An apparatus contains Br2(g) in a solution. What happens to the vapor pressure when the piston lowers and decreases the volume of Br2(g) above the solution by half? (Assume no temperature change).

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 10th, 2017, 2:21 pm

An apparatus contains Br2(g) in a solution. What happens to the vapor pressure when the piston lowers and decreases the volume of Br2(g) above the solution by half? (Assume no temperature change).
Attempt
I think it would double?
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

Piggy
Member
Member
Posts: 24
Joined: August 4th, 2015, 11:43 am
Division: C
State: NY

Re: Chem Lab C

Postby Piggy » February 10th, 2017, 4:25 pm

An apparatus contains Br2(g) in a solution. What happens to the vapor pressure when the piston lowers and decreases the volume of Br2(g) above the solution by half? (Assume no temperature change).
Attempt
I think it would double?
Incorrect.
Should I give the answer now or wait?

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 10th, 2017, 4:48 pm

An apparatus contains Br2(g) in a solution. What happens to the vapor pressure when the piston lowers and decreases the volume of Br2(g) above the solution by half? (Assume no temperature change).
Attempt
I think it would double?
Incorrect.
Should I give the answer now or wait?
Actually, I think I figured out my issue.
I think so at least
If I'm correct, I didn't pay proper attention to the fact that it's vapor pressure as opposed to "normal pressure"- I believe that the vapor pressure would remain the same, as some of the gas would condense into liquid Br2.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

Piggy
Member
Member
Posts: 24
Joined: August 4th, 2015, 11:43 am
Division: C
State: NY

Re: Chem Lab C

Postby Piggy » February 10th, 2017, 5:12 pm

Attempt
I think it would double?
Incorrect.
Should I give the answer now or wait?
Actually, I think I figured out my issue.
I think so at least
If I'm correct, I didn't pay proper attention to the fact that it's vapor pressure as opposed to "normal pressure"- I believe that the vapor pressure would remain the same, as some of the gas would condense into liquid Br2.
Correct! Your turn.

Avogadro
Member
Member
Posts: 66
Joined: January 6th, 2017, 4:51 pm
Division: Grad
State: PA
Location: Swarthmore College

Re: Chem Lab C

Postby Avogadro » February 13th, 2017, 10:38 am

According to the second law of thermodynamics, entropy must always increase. How is it, then, that it is possible for water to freeze and become ice? Justify your response using both an equation and a direct reference to the second law of thermodynamics.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2


Return to “2017 Question Marathons”

Who is online

Users browsing this forum: No registered users and 12 guests