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Topic: Pressure of a gas.  (Read 4801 times)

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Exit Strategy v1

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Pressure of a gas.
« on: August 02, 2005, 08:54:51 PM »
Wow. I am totally stumped. I am taking an at home Chemistry class just to improve my understanding of the subject better for next year at college and I came to this one question that seems easy but then it is so confusing.

What is the pressure of a gas if 300mL at 0.8 atm and 37 degrees C changes to 50 degrees C and 555mL?

Stumped totally. Any help on this one would be deeply appreciated.

Linkiroth

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Re:Pressure of a gas.
« Reply #1 on: August 02, 2005, 09:13:50 PM »
Combined Gas Law:

(P1 V1)/T1 = (P2 V2)/T2

Plug in the numbers and figure it out.
« Last Edit: August 02, 2005, 09:14:36 PM by Linkiroth »

Exit Strategy v1

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Re:Pressure of a gas.
« Reply #2 on: August 02, 2005, 09:18:59 PM »
whoops. I just put the values in the wrong way. thank you for correcting that formula for me.

what i got was:
0.8atm x 300mL/37 Degrees C = P1 555mL/50 Degrees C and got .58atm

Did I hit it?

Offline sdekivit

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Re:Pressure of a gas.
« Reply #3 on: August 03, 2005, 03:59:21 AM »
no, because you didn't use the absolute temperature in K. When you convert degrees C to kelvin and plug that number in, you'll get the correct answer.

camur

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Re:Pressure of a gas.
« Reply #4 on: August 08, 2005, 05:29:35 AM »
Remember the ideal gas equation PV=nRT  temperature scale must be in Kelvine. The number of moles and R are  constant.So PV/T will be constant.  
(0.8x300)/310=(P'x555)/323
then solve the equation for P'

Offline sdekivit

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Re:Pressure of a gas.
« Reply #5 on: August 08, 2005, 12:42:18 PM »
remember that in this case we have to plug in the temperature. This means the absolute temperature in K. In another formula, Q = c * m * delta T, we have to plug in a change in temperature and then we can plug in Celsius, since the change in Celsius equals the change in Kelvins.

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