Answer:
0.0386 atm
Explanation:
For a reversible reaction, the equilibrium is the point where the velocity of the formation of the products is equal to the velocity of the formation of the reactants. In equilibrium, the concentrations, or the partial pressures, don't change.
The equilibrium constant (K) may be calculated from de molar concentration (Kc) or from de partial pressure (Kp), which are, for a common reaction:
aA + bB ⇆ cC + dD
[tex]Kc = \frac{[C]^c.[D]^d}{[A]^a.[B]^b}[/tex]
[tex]Kp = \frac{(pC)^c.(pD)^d}{(pA)^a.(pB)^b}[/tex]
The partial pressure is given only for gases and the molar concentration for gases and liquids. So, for the reaction give:
PCl₅(g) ⇆ PCl₃(g) + Cl₂(g)
0.123 0 0 Initial
-x +x +x Reacted
0.123-x x x Equilibrium
[tex]Kp = \frac{(pPCl3).(pCl2)}{(pPCl5)}[/tex]
[tex]0.0121 = \frac{x.x}{0.123-x}[/tex]
Supposing x<<0.123 :
x² = 0.123x0.0121
x² = 1.4883x10⁻³
x = √1.4883x10⁻³
x = 0.0386 atm
Which is the partial pressure of PCl₃.
