Ideal Gas Equation: Calculating R in PV=nRT

In summary: Then solve for R.In summary, the ideal gas equation, PV=nRT, can have different units for each variable, such as bar for pressure (P), cubic meters for volume (V), moles for amount (n), and kelvin for temperature (T). To solve for R, the gas constant, the given units for each variable must be converted to the standard units of liters, atmospheres, moles, and kelvin. Once all units are converted, R can be solved for using the ideal gas equation.
  • #1
Dodabby
2
0

Homework Statement



The ideal gas equation, PV=nRT, may have the following units:
P is given in bar (bar)
V is given in m3 (cubic meters)
N is given in mol (moles)
T is given in K (kelvin)

Which value of R would you use for the calculation if you were using the above units for the other variables in the calculation?

Homework Equations



Dont have any.

The Attempt at a Solution



I have no attempt at the solution as i honestly do not understand how to come to a conclusion. I am a first year university student, having just started a degree in Biochemistry - and i have three basic chemistry modules to complete before i can get onto Biochemistry.

This being a career change for me at age 34, and not having done science in school, i am really stuck and have been battling on this question for a week now.

Any help would be greatly appreciated - just an explanation of where to start would be of great help.

Thanks!
 
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  • #2
Solve for R - and replace given symbols (P, V, n, T) with units.

--
methods
 
  • #3
The gas constant's value is determined by its units. If you alter the units you need to alter the value of the constant also. The gas constant is joules per (kelvin x mol). If you multiply pressure in pascals by volume in metres you get joules. Since your volume is in metres already, you need to find out the relationship between pascals and bar.
At least, I think that's correct...
 
  • #4
Borek said:
Solve for R - and replace given symbols (P, V, n, T) with units.
You beat me Borek!
Is what I said reliable?
 
  • #6
Thank you for the response :)

Problem is - the question is exactly as i typed it. There are no units given, at all. Hence why i am stumped :/

Have they perhaps made a mistake, or am i really being clueless?
 
  • #7
Dodabby said:
P is given in bar (bar)
V is given in m3 (cubic meters)
N is given in mol (moles)
T is given in K (kelvin)

No units?

--
methods
 
  • #9
You could start with [tex]R = 0.0821 \frac{L\cdot atm}{mol\cdot K}[/tex] and convert the pressure and volume to the other units.
 

FAQ: Ideal Gas Equation: Calculating R in PV=nRT

What is the Ideal Gas Equation?

The Ideal Gas Equation is a fundamental equation in thermodynamics that describes the relationship between the pressure, volume, temperature, and number of moles of an ideal gas. It is given by the formula PV=nRT, where P is the pressure, V is the volume, T is the temperature, n is the number of moles, and R is the universal gas constant.

What is the value of R in the Ideal Gas Equation?

The value of R in the Ideal Gas Equation depends on the units used for pressure, volume, and temperature. In SI units, the value of R is 8.314 Joules/mol·K. In other commonly used units, R can be expressed as 0.0821 L·atm/mol·K or 62.36 L·Torr/mol·K.

How do you calculate R in the Ideal Gas Equation?

R can be calculated by rearranging the Ideal Gas Equation to solve for R: R = (PV)/(nT). To do this, you will need to know the values of pressure, volume, temperature, and number of moles for a given gas sample. Once you have these values, you can simply plug them into the equation and solve for R.

What is the significance of R in the Ideal Gas Equation?

R is a constant that relates the macroscopic properties of a gas (pressure, volume, and temperature) to the microscopic properties (number of moles). It is a fundamental constant in thermodynamics and is used in various gas laws and equations to describe the behavior of gases under different conditions.

Can the Ideal Gas Equation be applied to real gases?

The Ideal Gas Equation is an approximation that is often used for real gases under certain conditions, such as low pressures and high temperatures. However, it does not take into account the intermolecular forces and volume of the gas molecules, so it may not accurately describe the behavior of all real gases. In these cases, more complex equations or corrections must be applied to accurately describe the gas behavior.

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