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Topic: Enthalpy and Rate Constant  (Read 9287 times)

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Offline TEA1

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Enthalpy and Rate Constant
« on: April 14, 2008, 09:02:47 PM »
I have 2 questions I need a little help on. Thanks

1. Consider the thermal decomposition of CaCO3.
CaCO3(s)  CaO(s) + CO2(g)

The equilibrium vapor pressures of CO2 are 22.6 mmHg at 700°C and 1829 mmHg at 950°C. Calculate the standard enthalpy of the reaction.

2. The rate constant for the elementary reaction is 7.1  109/M·s at 25°C.
2 NO(g) + O2(g)  2 NO2(g)

What is the rate constant for the reverse reaction at the same temperature?

Offline Valdorod

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Re: Enthalpy and Rate Constant
« Reply #1 on: April 15, 2008, 12:39:42 PM »
1) you need to use the Clausius-Clapeyron Equation

ln(p1/p2) = H/R(1/t1-1/t2)

you have p1, t1, p2, t2.  R is the ideal gas constant 8.314 x 10-3 kJ/K*mol

solve for H(enthalpy)

2) Krev = K-1, thus just take the inverse.

Valdo

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