Constants I Periodic Table Part A ou may want to reference P

Constants I Periodic Table Part A ou may want to reference (Pages 656-664) Section 5.8 while completing this problem. Find the equilibrium concentration of S2 Express the concentration to three significant figure Consider the reaction for the decomposition of hydrogen disulfide: 2H2S(g) 2H2 (g) +S2(g), Kc = 1.67 x 10-7 at 800°C The reaction is carried out at the same temperature with the following initial concentrations [H2S] = 4.30 x 10-4M [H21-0.00 M [S2] 0.00 M S2lValue its Submit Previous Answers

Solution

The reaction is 2H2S(g) <------------> 2H2(g)+ S2(g)

Equilibrium constant = K= [S2] [H2]²/ [H2S]²= 1.67*10^-7,

preparing the ICE table

component                                       initial                         change                   equilibrium

H2S                                                4.3*10^-4                           -2x                    4.3*10^-4-2x

H2                                                     0                                    2x                                2x

S2                                                    0                                      x                                  x

K= x*(2x)²/ (4.3*10^-4-2x)²= 1.67*10^-7 ,

x³/(4.3*10^-4-2x)²= 1.67*10^-7/4= 4.2*10^-8

when solved for x using excel, x= 1.87*10^-5

hence at equilibrium, [S2]=1.87*10^-5 M , [H2]=2*1.87*10^-5= 3.74*10^-5M, H2S= 4.3*10^-4-2*1.87*10^-5=0.0003926