W (s) + 4 Br(g) WBr4(g) At the walls of the lamp, where the temperature is about

Question

W (s) + 4 Br(g) WBr4(g) At the walls of the lamp, where the temperature is about 900 K, this reaction has an equilibrium constant K, of about 100. If the equilibrium pressure of Br(g) is 0.010 atm, what is the equilibrium pressure of WBr4(g) near the walls of the bulb? Near the tungsten filament, where the temperature is about 2800 K, the reaction in part (a) has a K, value of about 5.0. Is the reaction exothermic or endothermic? When the WBr4(g) diffuses back toward the filament, it decomposes, depositing tungsten back onto the filament. Show quantitatively that the pressure of WBr4 from part (a) will cause the reaction in part (a) to go in reverse direction at 2800 K. [The pressure of Br(g) is still 0.010 atm.) Thus, tungsten is continually recycled from the walls of the bulb back to the filament, allowing the bulb to last longer and bum brighter. The decomposition of solid ammonium carbamate, (NH4)(NH2C02), to

Explanation / Answer

Total pressure=P=p(NH3) +p(CO2) [dalton's law of partial pressures)

where p(NH3) =partial pressures of NH3

p(CO2) =partial pressures of CO2

Also p(NH3)=X (NH3) *P (raoult's law),               [X (NH3)=mole fraction of NH3,X(CO2)=mole fraction of CO2]

p(CO2)=X(CO2) *P

Also X(CO2)+X (NH3)=1

for the given equilibrium,

kp=p(NH3)^2 *p(CO2)=[X(CO2) *P]^2 [X (NH3) *P]

from the equation we see, 2 moles of NH3=1 mole of CO2

so X(NH3)=2/3 , X(CO2)=1/3

kp=[(2/3)*P]^2 (1/3) *P=4/27 *P^3=4/27 * (0.116 atm)=0.0172

kp=0.0172 atm

b)1)Adding CO2=would decrease the amount of NH3 as rate of reverse reaction will increase.

2)Adding(NH4)(NH2CO2) would increasee the amount of NH3 as rate of forward reaction will increase.

3)Removing CO2 would increasee the amount of NH3 as rate of forward reaction will increase

4)Increasing the total volume would decrease the total pressure on the product side, So the amount of NH3 will increase as rate of forward reaction will increase

5)Adding Neon, will increase the pressure, thereby compressing the products and incresing the rate of reverse rxn.The amount of NH3 will decrease.

6)Increasing temperature will increase the kinetic energy of gaseous species, increase in volume and so reduction in pressure on product side.So the amount of NH3 will increase as rate of forward reaction will increase/

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