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# physical chemistry question watch

1. Hi, could somebody help me with this please? We haven't covered it in lessons and can't seem to find much about it. Is this to do with K/Kc?
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2. As far as I am aware no current A level specs expect you to know about Kp
3. (Original post by jacksonmeg)
Hi, could somebody help me with this please? We haven't covered it in lessons and can't seem to find much about it. Is this to do with K/Kc?
Kp (the equilibrium constant with regard to gas pressures) is given by the partial pressure raised to its coefficient in the balanced equation of products over reactants.
4. (Original post by GDN)
As far as I am aware no current A level specs expect you to know about Kp
Nah we didn't do Kp
5. (Original post by charco)
Kp (the equilibrium constant with regard to gas pressures) is given by the partial pressure raised to its coefficient in the balanced equation of products over reactants.
Ah ty I had no idea what it was, ill go look it up now
6. (Original post by charco)
Kp (the equilibrium constant with regard to gas pressures) is given by the partial pressure raised to its coefficient in the balanced equation of products over reactants.
also do you know how I can convert enthalpy of vaporization to entropy of vaporization? I'm getting a bit bogged down with enthalpy/entropy as topics, too many formulas and too much maths.
7. (Original post by jacksonmeg)
also do you know how I can convert enthalpy of vaporization to entropy of vaporization? I'm getting a bit bogged down with enthalpy/entropy as topics, too many formulas and too much maths.
You can't convert enthalpy to entropy, they are entirely different concepts.
8. (Original post by charco)
You can't convert enthalpy to entropy, they are entirely different concepts.
The question is ''The normal boiling point of hydrogen is 20.4K and the enthalpy of vaporisation at this temperature is 916 J mol^-1. Calculate the entropy of vaporisation''
9. (Original post by jacksonmeg)
The question is ''The normal boiling point of hydrogen is 20.4K and the enthalpy of vaporisation at this temperature is 916 J mol^-1. Calculate the entropy of vaporisation''
At the temperature of a phase change there is an equilibrium between the two phases. This means that Gibbs free energy change is zero and as:

ΔG = ΔH - TΔS

Then at equilibrium:

ΔH = TΔS
10. (Original post by charco)
At the temperature of a phase change there is an equilibrium between the two phases. This means that Gibbs free energy change is zero and as:

ΔG = ΔH - TΔS

Then at equilibrium:

ΔH = TΔS
Ahhh ty I didn't know that

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