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1. Determine the equilibrium expression for the following reaction 2 NaHCO 3 (s)

ID: 976660 • Letter: 1

Question

1.     Determine the equilibrium expression for the following reaction

2 NaHCO3 (s)   Na2CO3 (s) + H2O (g) + CO2 (g)

2.     Kc = 5.6 × 10-12 at 500 K for the reaction

I2 (g)          2 I (g)

A mixture is kept at 500 K and before equilibrium is reached, I2 has a concentration of 0.02 M and I has a concentration of 0.00000002 M. Which direction must the reaction lie to reach equilibrium.

3.     Given Kp = 1.5 × 1018 at 300 K for the reaction below

3 NO           N2O +   NO2

a.     Determine the Kc value at the same temperature.

b.     900 mg of NO were initially placed in a 1.00 L vessel and the reaction was allowed to reach equilibrium. Calculate the equilibrium concentrations of NO, N2O, and NO2.

4.     Calculate the Kc for the following reaction

SnO2   + 2CO          Sn + 2 CO2

      given the following information:

SnO2   + 2 H2          Sn + 2 H2O        Kc = 8.12

H2   + CO2          CO + H2O             Kc = 0.771

5.     Methanol is manufactured by the below catalyzed reaction using ZnO/Chromate.

CO (g) + 2 H2 (g)          CH3OH (g)          D H = -91 kJ

Does the amount of methanol (CH3OH) increase, decrease, or remain the same when an equilibrium mixture of reactants and/or products are subjected to the following changes?

a.     The temperature is decreased

b.     The volume is increased

c.     Methanol is added

d.

Explanation / Answer

1.   Determine the equilibrium expression for the following reaction

2 NaHCO3 (s) --- > Na2CO3 (s) + H2O (g) + CO2 (g)

Keq = PCO2 PH2O

Here NaHCO3 (s) and Na2CO3 (s) both present in solid form.

2.     Kc = 5.6 × 10-12 at 500 K for the reaction

I2 (g) --- >         2 I (g)

A mixture is kept at 500 K and before equilibrium is reached, I2 has a concentration of 0.02 M and I has a concentration of 0.00000002 M. Which direction must the reaction lie to reach equilibrium.

Now determined the Q fro the given reaction:

Q = product / reactants

Q= 0.00000002 / 0.02

Q=1.0*10^-6

And given that Kc = 5.6 × 10-12 at 500 K for the reaction

Here Q, 1.0*10^-6 > Kc, 5.6 × 10-12

When Q>K, there are more products than reactants. The direction of reaction is forward .

3.     Given Kp = 1.5 × 1018 at 300 K for the reaction below

3 NO   --- >       N2O +   NO2

The relation between Kp and Kc is given as;

Kp = Kc (RT)^n
Kp = 1.5 × 1018 at 300 K
Kp = equilibrium constant in terms of partial pressures (atm)
Kc = equilibrium constant in terms of concentrations(molarity)
R = ideal gas constant ( 0.082 atm.L / K.mol)
T = absolute temperature (300 K)
n = n products - n reactants
n = (2) - (3) =- 1

Kp = Kc (RT)^n
1.5 × 1018 at 300 K = (Kc) {(0.082)(300)}^-1
Kc = 3.69*10^19

b.     900 mg of NO were initially placed in a 1.00 L vessel and the reaction was allowed to reach equilibrium. Calculate the equilibrium concentrations of NO, N2O, and NO2.

4.     Calculate the Kc for the following reaction

SnO2   + 2CO   --->       Sn + 2 CO2

      given the following information:

Given that,

SnO2 (s) + 2H2 (g) <--> Sn (s) + 2H2O (g)

Kc1= 8.12 = [H2O]^2 / [H2]^2



H2 (g) + CO2 (g) <--> H2O (g) + CO (g)

Kc2 = 0.771 = [H2O] [CO] / [H2] [CO2]


To calculate the Kc for the following reaction

SnO2   + 2CO   --->       Sn + 2 CO2


Kc = [CO2]^2 / [CO]^2


first we take the inverse squared of Kc2,

(1/ Kc2)^2 = [H2]^2 [CO2]^2 / [H2O]^2 [CO]^2

Now the above equation is multiply with Kc1


(1/ K2)^2 X Kc1 =( [H2]^2 [CO2]^2 / [H2O]^2 [CO]^2 ) X ([H2O]^2 / [H2]^2 )

= CO2]^2 / [CO]^2
The above is the result of the given reaction.


K = (1/ K2)^2 X Kc1 = (1/ 0.771)^2 x (8.12)

K = 13.66