A-level Chemical Equilibrium

我想問,佢講 the total no. of moles of gas increases , the total pressure will increase.
係唔係因為 PV=nRT, 由於V係constant,所以no. of moles increase, so pressure increase.
唔知我呢個推論岩唔岩呢?

Yes, the induction is correct.
PV = nRT
P = (RT/V)n
As R, T and V are kept constant,
P = constant x n
Therefore, P (the total pressure) is directly proportional to n (the total number of moles of gases).


= = = = =
第2點, but this increase in pressure will not change the equilibrium position because the concentrations and the partial pressures of SO2,O2 and SO3 have not changed.
呢一段我唔係好明,請回答者清楚解釋一下,到底係點樣推斷出黎既呢?

2SO2(g) + O2(g) ⇌ 2SO3(g)

PV = nRT
Partial pressure of SO2, PSO2 = nSO2(RT/V)
Partial pressure of O2, PO2 = nO2(RT/V)
Partial pressure of SO3, PSO3 = nSO3(RT/V)
After addition of the inert gas, R, T, V and the numbers of moles of SO2, O2 and SO3 are kept constant. Therefore, all of the partial pressures of SO2, O2 and SO3 remain unchanged after the inert gas.

Before addition of the inert gas,
total pressure = PSO2 + PO2 + PSO3
After addition of the inert gas,
total pressure = PSO2 + PO2 + PSO3 + Pinert gas
Obviously, pressure increases by Pinert gas after the addition of the inert gas.

The equilibrium constant Kp = (PSO3)²/(PSO2)²(PO2)
After addition of the inert gas, KP is unchanged as all of the partial pressures of SO2, O2 and SO3, as well as the temperature, remain unchanged.
As Kp is unchanged, the equilibrium position will not be changed.