Solving Unknown Quantity of Gas: Help Appreciated!

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Homework Help Overview

The problem involves determining the number of moles of an unknown quantity of gas given its pressure, volume, and temperature. The context is rooted in gas laws, specifically the ideal gas law.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the appropriate equations to use, questioning whether to apply nRT or NkT. There is also a focus on ensuring correct unit conversions, particularly for pressure and volume.

Discussion Status

Participants are actively engaging with the problem, checking assumptions about units and clarifying the meanings of variables involved in the equations. Some guidance has been offered regarding unit consistency, but no consensus on the approach has been reached.

Contextual Notes

There is an emphasis on adhering to MKS units, with specific mention of converting volume from liters to cubic meters and pressure to pascals.

chawkdee
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If anyone has time, could you please show me the working of this problem.

Greatly appreciated


b]1. Homework Statement [/b]
If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature of 87C, how many moles of gas do I have?


Homework Equations



PV=nRT=NkT

The Attempt at a Solution



1.2 x 31=n8.3145 x (87+273)= N x 1.38066x10*23 x (87+273)

Can you tell me if the above numbers are correct please.
 
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chawkdee said:
If anyone has time, could you please show me the working of this problem.

Greatly appreciated


b]1. Homework Statement [/b]
If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature of 87C, how many moles of gas do I have?


Homework Equations



PV=nRT=NkT

The Attempt at a Solution



1.2 x 31=n8.3145 x (87+273)= N x 1.38066x10*23 x (87+273)

Can you tell me if the above numbers are correct please.
You have to stick to MKS units. Volume has to be in m^3 not litres. Otherwise, it looks fine.

AM
 
The pressure should be in pascals as well.
 
phsopher said:
The pressure should be in pascals as well.

Of course! Thanks for catching that.

AM
 
chawkdee said:
... how many moles of gas do I have?


Homework Equations



PV=nRT=NkT

Given what is being asked, would you use nRT or NkT here?
 
Redbelly98 said:
Given what is being asked, would you use nRT or NkT here?

nRT ??
 
Why do you think that ... or is it just a random guess? The key here is: what do n and N mean?
 
Redbelly98 said:
Why do you think that ... or is it just a random guess? The key here is: what do n and N mean?

n - number of moles

N - number of molecules
 
Okay, yes. n is the number of moles, so PV=nRT is the thing to use here.

Just be careful with the units, as others said earlier.
 

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