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Dassinia
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Hello
I'm solving previous exams and there is this exercise that appears in almost every exam :
Suppose v moles of a gas H2O are enclosed in a constant volume V at a low temperature so the gas is in aN undissociated state. At highest temperatureS, H2O molecules are dissociated
2H2O-> 2H2 + O2
If "f" is the fraction of H2O molecules that are dissociated at a known temperature T, and p the total pressure of the gas at that temperature, show that Kp(T) at this pressure is :
Kp(T)= p f^3/ (( 1-f)^2(2+f) )
Kp(T)=[ (P02)*PH2² ]/(PH20)²
We have Pi=xi*p
Kp(T)= [ x02*p*(xH2*p)² ]/(xH20*p)²
Kp(T)= [ p*x02*xH2² ]/xH20²
xi=ni/ntot
Kp(T)= [ p*n02*nH2² ]/(nH20²*ntot)
nH20²=(1-f)²
but I don't get why ntot=2+f and n02=nH2=f
I'm solving previous exams and there is this exercise that appears in almost every exam :
Homework Statement
Suppose v moles of a gas H2O are enclosed in a constant volume V at a low temperature so the gas is in aN undissociated state. At highest temperatureS, H2O molecules are dissociated
2H2O-> 2H2 + O2
If "f" is the fraction of H2O molecules that are dissociated at a known temperature T, and p the total pressure of the gas at that temperature, show that Kp(T) at this pressure is :
Kp(T)= p f^3/ (( 1-f)^2(2+f) )
Homework Equations
The Attempt at a Solution
Kp(T)=[ (P02)*PH2² ]/(PH20)²
We have Pi=xi*p
Kp(T)= [ x02*p*(xH2*p)² ]/(xH20*p)²
Kp(T)= [ p*x02*xH2² ]/xH20²
xi=ni/ntot
Kp(T)= [ p*n02*nH2² ]/(nH20²*ntot)
nH20²=(1-f)²
but I don't get why ntot=2+f and n02=nH2=f
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