# Universal and Individual Gas Constant

• Altairs
In summary, the notes cover the relationship between pressure, volume, temperature, and gas constant. There is some confusion about which gas constant (universal or individual) is used in the equation, and whether molar volume and specific volume are the same thing. The notes also mention different values for the gas constant, which may be due to a typo or different units. More clarification is needed.
Altairs
I got injured while playing football and had to miss a Thermodynamics-I lecture. Got the notes afterwards but they tend to make things more complicated. The notes starts with :-

$$Pv=RT$$

Which R is this the Universal Gas Constant or the Individual Gas Constant ?

Is the Molar Volume and Specific Volume same thing?

Then it says $$R = \frac{R_{u}}{Mol Wt.}$$, which seems alright.

Then it says that :-

For EE :-

$$R = \frac {1545}{Mol Wt.}$$

For SI :-

$$R = \frac {8314}{Mol Wt.}$$

Question is that I have always seen the Molar Gas Constant to be $$8.134 JK^{-1}mol^{-1}$$. How does 8314 come ?

I'll be obliged if someone can give systematic answers. this way my confusion will be eliminated.
(looks like there's some problem with LaTex)

Last edited:
Altairs said:
I got injured while playing football and had to miss a Thermodynamics-I lecture. Got the notes afterwards but they tend to make things more complicated. The notes starts with :-

$$Pv=RT$$

Which R is this the Universal Gas Constant or the Individual Gas Constant ?
It could be either, depending on whether v is the volume per mole or the volume per unit mass.
Is the Molar Volume and Specific Volume same thing?
Molar Volume is volume per mole and Specific Volume is volume per unit mass
Then it says $$R = \frac{R_{u}}{Mol Wt.}$$, which seems alright.

Then it says that :-

For EE :-

$$R = \frac {1545}{Mol Wt.}$$

For SI :-

$$R = \frac {8314}{Mol Wt.}$$

Question is that I have always seen the Molar Gas Constant to be $$8.134 JK^{-1}mol^{-1}$$. How does 8314 come ?

I'll be obliged if someone can give systematic answers. this way my confusion will be eliminated.
(looks like there's some problem with LaTex)
It's not clear. It could be a typo.

## What is the Universal Gas Constant?

The Universal Gas Constant (represented by the symbol R) is a physical constant that relates the properties of a gas to its temperature, pressure, and volume. It is equal to 8.314 joules per mole-kelvin (J/mol·K) in the International System of Units (SI).

## What is the Individual Gas Constant?

The Individual Gas Constant (represented by the symbol Ri) is a specific gas constant for a particular gas. It is equal to the universal gas constant divided by the molar mass of the gas. This allows for the calculation of the gas constant for different gases in different units.

## What is the difference between Universal and Individual Gas Constant?

The main difference between the Universal and Individual Gas Constant is that the Universal Gas Constant is a constant value that applies to all gases, while the Individual Gas Constant varies depending on the specific gas and can be calculated using the universal gas constant and the molar mass of the gas.

## How do you calculate the Universal Gas Constant?

The Universal Gas Constant can be calculated using the ideal gas law equation, which states that PV = nRT, where P is pressure, V is volume, n is the number of moles, T is temperature, and R is the universal gas constant. Rearranging the equation to solve for R gives the formula R = PV/nT.

## What are the units of the Universal Gas Constant?

The units of the Universal Gas Constant vary depending on the units used for pressure, volume, and temperature in the calculation. However, the most commonly used units are joules per mole-kelvin (J/mol·K) in the International System of Units (SI).

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