Question

General Chemistry II b) Would you expect AE to be the same as AH for this reaction? Explain. (.5 pt) 3. Calculate AG for the reaction C(diamond) + O2(g) → CO2(g) Given the result of your calculation, postulate a reason for why we dont protect diamonds from atmospheric oxygen? (1.5 pt) 4. Consider the dimerization reaction 2 NO2) = N20.g) at 298 K. If the starting pressure of NO2(g) 0.011 atm and that of N:0.9) was 0.065 atm, would this reaction proceed forwards or backwards? (2 pt)

Answer 1

Multiple questions as per guideline only first (1) will be answered :

1.

Clausius-Clapeyron Equation and allows us to estimate the vapor pressure at another temperature, if the vapor pressure is known at some temperature, and if the enthalpy of vaporization is known.

if P1 and P2 are the vapor pressures at two temperatures T1 and T2, then a simple relationship can be found:

ln(P1/ P2) = (ΔHvap / R)(1/T2 − 1/T1)

For water,  ΔHvap = 40.7 kJ/mol = 40700 J/mol

at 393 K (T2) , we have P2 = 1 atm.

so using equation :

ln(P1/ 1 atm) = (40700 J/mol / 8.314 J/K-mol ) (1/393 K − 1/298 K)

or   ln(P1/ 1 atm) = - 3.304

or P1  = 0.0369 atm.

so, vapour pressure of water will be 0.0367 atm.