Question

part a

the reaction COCl2(g)<-->CO(g)+Cl2(g) has an equilibrium constant Kc=2.19*10^-10 at 100 degree celcius. is the following mixture at equilibrium, and if not, which direction must it shift to reach equilbrium? [COCl2]=3.30*10^-3 M, [CO]=6.2*10^-9 M, [Cl2]=2.00*10^-9 M

part b

when additional lead ions are added to a saturated solution of PbSO4, which direction will the reaction shift?

part c

what is the pH of a 0.015 M solution of NaOH?

part d

the reaction 2SO2(g)+O2(g)<-->2SO3(g) has an equilibrium constant, Kp=0.345 at 900K. in an equilibrium mixture the pSO2=0.135 atm and pO2=0.455, what is the partial pressure of SO3 in the mixture?

Answer 1

Part a :

COCl2(g) <--> CO(g) + Cl2(g)

Concentrations(M) 3.30x10^-3 6.2x10^-9 2.00x10^-9

reaction quotient , Q = ([CO][Cl2]) / [COCl2]

= (2.00x10^-9 x 6.2x10^-9 )/ (3.30x10^-3)

= 3.75x10^-15

Given  K_c=2.19*10^-10

Q < Kc so the reaction is not at equilibrium.

Part b :

According to the Le-Charterlier's principle, If the concentration of reactants is increased or product is removed , the reaction will take place in the forward direction. If the concentration of reactants decreases or increasing the concentration of products the reaction will take place in the backward direction.

When Pb²⁺ ions are added there is no change in the position.

Part c :

Given [NaOH] = 0.015 M

[OH-]=[NaOH] = 0.015 M

pOH = - log[OH-] = - log 0.015 = 1.82

pH = 14 - pOH = 12.18

Part d :

2SO2(g)+O2(g)<-->2SO3(g)

Equb pressure (atm) 0.135 0.455 x

Kc = p2 SO3 / (p2SO2 x p O2) = 0.345

x² / ( 0.135² x 0.455) ) = 0.345

x = 0.053 atm

So the partial pressure of SO3 is 0.053 atm