Question

One mole of H20( is supercooled to-5.00°C at 1 bar pressure before freezing at that temperature. Calculate ASys, ASum, and ASeotal for this process. Is it spontaneous? CPm (H20, 1)- 75.3 J/mol.K CPm (H20, s)-37.7 J/mol.K AHfusion 6.008 kJ/mol Hint: remember that ASs is computed using q along a reversible path, while ASur is computed using the actual heat transfer during the freezing. For the following equilibrium reaction: Here is an ICE table, starting from no moles of pure 0z 302(g) no 3x no-3x 203(g) +2x 2x Define "extent of reaction as a x/no Following the example we did in class for Cl2 dissociation, show here that, at equilibrium: Hint: Kp for the reaction of 02 to Os is TINY (oxygen doesn't readily form ozone at standard conditions). So, you can easily assume that no>>x, and x is negligible compared to no- Find the extent of reaction a at 298 K and a pressure of 110 bar. You will need a value of KP, but you can figure that out from AGr data in the back of the book. 1.55 moles of Argon gas undergo an isothermal reversible expansion from an initial volume of 5.00 L to 105.L at 200 K. Calculate the work done during this process using: (a) the ideal gas equation, and (b) the van der Waals equation of state. Van der Waals parameters for Ar are available in the back of the book. Compare the two results, what percentage of the work done by the van der Waals gas arises due to having to overcome the attractive potential? Tin has two solid forms, Sn(s.gray) and Sn(s,white), that are at equilibrium with each other at 1 bar and 18°C. If pressure changes to 80 bar, at which temperature would these two phases be in equilibrium? You can assume volume and entropy of these two phases are unaffected by the pressure change. The density of gray tin is 5750 kg.m3, and its molar entropy is 44.14 J.K-mol1. The density of white tin is 7280 kg.m-3, and its molar entropy is 51.18 J.Kmol-1

Answer 1

Question 1.

Delta S_sys = nC_P, m (H_2O, l) ln (T_1/T_2) - n Delta H_fusion/T_1 + n_C_p, m (H_2O, s) ln (T_2/T_1) = 1 mol times 75.3 J/mol.k ln (0 + 273.15 k/-5 + 273.156) - 1 mol times 6008 J/mol/0 + 273.15 k + 1 mol times 37.7 J/mol k ln (-5 + 273.15 k/0 + 273.15 k) = 1.3911 J/k - 21.9952 J/k + (-0.6965 J/k) Delta S_sys = -21.30 J/k \r\n Delta S_surr = -q/T_surr = -n Delta H_fusion/T_2 = -6008 J/mol times 1 mol/-5 + 273.15 k Delta S_surr = -22.4054 J/k Delta S_total = 43.71 J/k