Through the three gas transformations (isothermal, isobaric, isovolumetric) represented respectively by the equations: PV = K, V/T = K, P/T = K, the General Gas Equation was reached:
Note that the equation addresses the three state variables (P, V, and T). Therefore, it is possible to know the volume, temperature and pressure of a gas if we base ourselves on this equation.
Let's look at an example:
The diagram above represents the transformations of a fixed mass of gas, based on it we can answer the following questions:
- What is the gas pressure value at the point THE? Note that point A is located at the value 2.0 in vector P (atm), so we say that the atmospheric pressure value at A is 2 atm.
- And the pressure value at the point B? Note that this point is at the same position as A with respect to vector P (atm). Therefore, B obeys the same conditions as A and has the same pressure: 2 atm.
- What gaseous transformation occurs in the passage from A to B?
Isobaric transformation, as the gas pressure is constant (2 atm) and the volume varies, from 4 liters (point A) to 8 liters (point B).
- And the volume at the point Ç? If we subtract B – A, we get the volume of C = 4 liters.
- Considering C and A: the pressure at these points varies, but the volume does not. We then have an Isovolumetric gas transformation.
By Líria Alves
Graduated in Chemistry
Brazil School Team
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gas transformations
General chemistry - Chemistry - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/quimica/equacao-geral-dos-gases.htm