According to PV=nRT,if we increase temp,no of moles will decrease,but no of moles is dependent on mass,mass is constant,then how can moles change?

We know the ideal gas equation is PV=nRT,then, according to this,if we keep Pressure,volume to be constant,then on increasing temperature,no of moles will reduce,this would mean that mass of matter or particles of the gas would simply vanish????how????how is conservation of mass followed here?




There are only 2 ways how to change the molar amount of gas ($n$) in the system:


* We add/remove some gas, so the system is open and the mass conservation law does not apply on the system content.
* There is ongoing chemical ( or nuclear ) reaction with different number of reactant and product entities and $n$ is changing due that.


Otherwise, $n$ is given as a fixed parameter. As $R \approx \pu{8.314 J K-1 mol-1}$ is a physical constant, we can reduce equation


$$pV = nRT$$


to


$$\frac{pV}{T} = a$$


where $a = nR$.


We can freely change any two of all three quantities ($p$, $V$, $T$), but the remaining third one is fully determined by values of the other two.


So $p=f(T,V)$, or $V=f(T,p)$ or $T=f(p,V)$.


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