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1 . The equilibrium 2NO(g)+Cl2(g)?2NOCl(g) is established at 500 K. An equilibri

ID: 933785 • Letter: 1

Question

1. The equilibrium
2NO(g)+Cl2(g)?2NOCl(g)
is established at 500 K. An equilibrium mixture of the three gases has partial pressures of 9.2010?2atm , 0.177atm , and 0.29atm for NO, Cl2, and NOCl, respectively.
Part A
Calculate Kp for this reaction at 500.0 K.
Express your answer using two significant figures.
Part B
If the vessel has a volume of 4.40L , calculate Kc at this temperature.
Express your answer using two significant figures.
2. If 8.0 g
of NH4HS(s) is placed in a sealed vessel with a volume of 1.0 L and heated to 200 ?C the reaction NH4HS(s) ? NH3(g) + H2S(g) will occur. When the system comes to equilibrium, some NH4HS(s) is still present. Which of the following changes will lead to a reduction in the amount of NH4HS(s) that is present, assuming in all cases that equilibrium is re-established following the change?
If 8.0  of  is placed in a sealed vessel with a volume of 1.0  and heated to 200  the reaction  will occur. When the system comes to equilibrium, some  is still present. Which of the following changes will lead to a reduction in the amount of  that is present, assuming in all cases that equilibrium is re-established following the change?

Adding more H2S(g) to the vessel
Adding more NH4HS(s) to the vessel
Increasing the volume of the vessel
Adding more NH3(g) to the vessel
Decreasing the volume of the vessel

Explanation / Answer

1. The equilibrium 2NO(g)+Cl2(g)?2NOCl(g) is established at 500 K. An equilibrium mixture of the three gases has partial pressures of 9.2010?2atm , 0.177atm , and 0.29atm for NO, Cl2, and NOCl, respectively.
Part A
Calculate Kp for this reaction at 500.0 K.

Kp is defined as Kp = P-products / P-. reactatns ratio

Kp = (P-NOCl)^2 / ((P-NO^2)(P-Cl2))

substitute data in equilbirium

Kp = (0.29)^2 / ((0.177)(9.2*10^-2)^2)

Kp = 56.136 --> 2 sig fig are expressed as 56

Kp = 56
Express your answer using two significant figures.
Part B
If the vessel has a volume of 4.40L , calculate Kc at this temperature.

Relate as:

Kp = Kc*(RT)^dn

dn = mol of products - mol of reactants = 2 - (2+1) = -1

substitute

Kp = Kc*(RT)^dn

56.136 = Kc*(0.082*500)^(-1)

Kc = 56.136 *0.082*500

Kc = 2301.576

round up to 2 sig fig --> 2300

Express your answer using two significant figures.

Question 2.

2. If 8.0 g of NH4HS(s) is placed in a sealed vessel with a volume of 1.0 L and heated to 200 ?C the reaction:

NH4HS(s) ? NH3(g) + H2S(g) will occur.

When the system comes to equilibrium, some NH4HS(s) is still present.

Which of the following changes will lead to a reduction in the amount of NH4HS(s) that is present, assuming in all cases that equilibrium is re-established following the change?

Adding more H2S(g) to the vessel --> True, the shift goes from right to left
Adding more NH4HS(s) to the vessel --> false, the final amount in equilibrium will be larger than original
Increasing the volume of the vessel --> increasing volume decreases concentration for gases, which favour even more production of gases, this is false
Adding more NH3(g) to the vessel --> true, since NH3 is a product, will form more reactatnts due to the shift in equilibrium
Decreasing the volume of the vessel --> True, as V decreases, The Q quotient incrases, favouring eventually more solid formation