Chem Lab C

Test your knowledge of various Science Olympiad events.
kenniky
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Re: Chem Lab C

Post by kenniky »

Avogadro wrote:I guess I'll answer that.
12.2 °C
correct, you can ask a question now
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Re: Chem Lab C

Post by Avogadro »

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.
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Code: Islip | Conestoga | Tiger | Regionals | States
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kenniky
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Re: Chem Lab C

Post by kenniky »

Avogadro wrote: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.
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
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Re: Chem Lab C

Post by Avogadro »

kenniky wrote:
Avogadro wrote: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.
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.
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Re: Chem Lab C

Post by kenniky »

15g of CaCl2 is added to 100 mL of water. What is the resultant boiling point of the water? (assume standard conditions)
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Re: Chem Lab C

Post by Avogadro »

kenniky wrote: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.

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
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Re: Chem Lab C

Post by kenniky »

Avogadro wrote:
kenniky wrote: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.

100.7 °C?
Incorrect, check your equation again (I'm pretty sure I know where you went wrong)
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Re: Chem Lab C

Post by Piggy »

kenniky wrote: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?
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Re: Chem Lab C

Post by kenniky »

Piggy wrote:
kenniky wrote: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
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Re: Chem Lab C

Post by Piggy »

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).
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