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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: Ice-cream on May 15, 2005, 08:06:23 AM

Title: equilibrium pressure question, plz help
Post by: Ice-cream on May 15, 2005, 08:06:23 AM
hey can any1 help me out?

At 900degrees C, Kp = 1.04 for the reaction
CaCO3 (s) --> CaO(s) + CO2(g)
At a low temperature, dryi ice (solid CO2), calcium oxide and calcium carbonate are introduced into a 50L reaction chamber. The temperature is raised to 900dgrees C, resulting in the dry ice converting to gaseous CO2. For the following mixtures, will the initial amount of calcium oxide increase, decrease or remain the same as the system moves toward equilibrium at 900degrees C?
a) 655g CaCO3, 95.0g CaO, P(CO2) = 2.55atm
b) 780g CaCO3, 1.00g CaO, P(CO2) = 1.04atm

I can do the rest (part  c and d) if i know how to do a) or b) so can any1 tell me how i'm meant to approach this question? i really don't know how to start it. for one thing, i realise that only gases would be participating in calculating the pressure equilibrium.

they say the answer is "decreases".
Title: Re:equilibrium pressure question, plz help
Post by: Borek on May 15, 2005, 09:08:31 AM
I am not quite sure if I understand the question properly:

Quote
655g CaCO3, 95.0g CaO, P(CO2) = 2.55atm

What P(CO2) = 2.55 atm stands for? Is this pressure just after heating, but before equilibrium is reached? If so, that's the simplest equlibrium question I have ever seen ;) You know what the equlibrium CO2 pressure should be, so you know whether CO2 have to be asborbed by the CaO or produced from CaCO3. Case b is even simpler then simple  ;D
Title: Re:equilibrium pressure question, plz help
Post by: Ice-cream on May 15, 2005, 09:36:15 AM